Little Giant Ladder Systems, LLC v. Tricam Industries, Inc.

Case: 24-2115     Document: 55    Page: 1     Filed: 02/05/2026




        NOTE: This disposition is nonprecedential.


   United States Court of Appeals
       for the Federal Circuit
                   ______________________

      LITTLE GIANT LADDER SYSTEMS, LLC,
                Plaintiff-Appellant

                             v.

                TRICAM INDUSTRIES, INC.,
                     Defendant-Appellee
                   ______________________

                         2024-2115
                   ______________________

     Appeal from the United States District Court for the
 District of Minnesota in No. 0:20-cv-02497-KMM-ECW,
 Judge Katherine Marie Menendez.
                 ______________________

                  Decided: February 5, 2026
                   ______________________

     MARK A. MILLER, Dorsey & Whitney LLP, Salt Lake
 City, UT, argued for plaintiff-appellant. Also represented
 by BRETT L. FOSTER, ELLIOT HALES; SHANNON L.
 BJORKLUND, Minneapolis, MN.

    ERIC HUGH CHADWICK, DeWitt LLP, Minneapolis, MN,
 argued for defendant-appellee.   Also represented by
 ZACHARY PAUL ARMSTRONG.
                ______________________
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 2                       LITTLE GIANT LADDER SYSTEMS, LLC v.
                                     TRICAM INDUSTRIES, INC.


     Before REYNA and CHEN, Circuit Judges, and FREEMAN,
                       District Judge.1
 CHEN, Circuit Judge.
     Little Giant Ladder Systems, LLC (Little Giant) ap-
 peals a decision of the United States District Court for the
 District of Minnesota granting summary judgment of non-
 infringement of 

U.S. Patent No. 10,767,416

 (’416 patent) in
 favor of Tricam Industries, Inc. (Tricam). See Little Giant
 Ladder Sys., LLC v. Tricam Indus., Inc., No. 20-CV-2497
 (KMM/ECW), 

2024 WL 1332027

 (D. Minn. Mar. 28, 2024),
 vacated in part (Apr. 12, 2024), modified and superseded by
 No. 20-CV-2497 (KMM/ECW), 

2024 WL 3014862

 (D. Minn.
 June 14, 2024) (D. Minn. June 14, 2024) (Summary Judg-
 ment Order).2 The district court determined that “the ac-
 cused products do not literally infringe the ‘cavity’
 limitation and prosecution history estoppel bars Little Gi-
 ant from relying on the doctrine of equivalents.” 

Id. at *1

.
 For the reasons below, we affirm.
                        BACKGROUND
     Little Giant and Tricam are competitors in the ladder
 industry. Summary Judgment Order, 

2024 WL 1332027

,
 at *1. Little Giant alleged that Tricam’s ladders use a lock-
 ing mechanism (called Speed Lock) that infringes the ’416
 patent. 

Id.

 at *2–3.
     The ’416 patent discloses a multi-position ladder with
 two sets of rails and a locking mechanism. ’416 patent, Ab-
 stract. The inventors recognized that operating a prior art
 ladder “can result in the pinching of one[’]s fingers or



       1 Honorable Beth Labson Freeman, District Judge,
 United States District Court for the Northern District of
 California, sitting by designation.
     2   The June 14, 2024 Order did not modify issues pre-
 sented in this opinion.
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                           3
 TRICAM INDUSTRIES, INC.


 hands” and “can be awkward and difficult for some people
 to perform.” 

Id.,

 col. 1 ll. 59–60; 

id.,

 col. 2 ll. 5–6. Accord-
 ingly, the ’416 patent is directed to improved ladders with
 “enhanced ease of use, stability[,] and safety.” 

Id.,

 col. 2 ll.
 17–21. The ‘416 patent has one independent claim, which
 recites:
     1. A ladder comprising:
         a first assembly having a first pair of rails
         including a first rail and a second rail, and
         a second pair of rails including a third rail
         and a fourth rail, the first pair of rails being
         slidably coupled with the second pair rails;
         and
         a first locking mechanism comprising:
             a first bracket coupled with the
             first rail,
             a first component rotatable about a
             defined axis,
             a first engagement pin coupled
             with the first component, wherein
             the first locking mechanism is con-
             figured so that the first component
             is rotatable from a first rotational
             position to a second rotational posi-
             tion;
             wherein, when the first component
             is in the first rotational position, a
             substantial amount of the first
             bracket is disposed within a cavity
             defined by the first component and
             the first engagement pin extends
             through a pair of aligned openings
             including a first opening formed in
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 4                        LITTLE GIANT LADDER SYSTEMS, LLC v.
                                      TRICAM INDUSTRIES, INC.


             the first rail and a second opening
             formed in third rail, and
             wherein, when the first component
             is in the second rotational position,
             the first engagement pin is with-
             drawn from at least one of the first
             opening and the second opening,
             at least one retaining mechanism
             configured to maintain the first
             component in the first rotational
             position until application of a first
             force is applied to the first compo-
             nent to displace it towards the sec-
             ond rotational position, and
             wherein the at least one retaining
             mechanism is further configured to
             maintain the first component in the
             second rotational position until ap-
             plication of a second force is applied
             to the first component.
 

Id.

 at claim 1 (emphasis added).3
      The disputed claim term “cavity” is recited in the con-
 text of a locking mechanism. The locking mechanism ena-
 bles height adjustment of the ladder by engaging or
 releasing the inner rails from the outer rails of the ladder.
 

Id.,

 col. 4 ll. 47–67 (descriptions of a ladder). The locking
 mechanism includes a bracket (“first bracket”) such as
 bracket 153 and a lever (“first component”) such as lever
 152. See 

id.,

 col. 2 ll. 31–32, 46–49; see also 

id.,

 FIG. 14.
 The lever is configured to pivot between two states: a
 locked state (“first rotational position”) shown in Figure



     3    The emphasized limitation is referred to as the cav-
 ity limitation.
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                        5
 TRICAM INDUSTRIES, INC.


 13A and an unlocked state (“second rotational position”)
 shown in Figure 13B.




 See ’416 patent, col. 7 ll. 26–31; 

id.,

 FIGs. 13A–B.
      The district court construed “cavity” to mean “a hol-
 lowed-out space (not passing all the way through).” Little
 Giant Ladder Sys., LLC v. Tricam Indus., Inc., No. 20-CV-
 2497 (KMM/ECW), 

2022 WL 2287048

, at *8–10 (D. Minn.
 June 24, 2022) (Claim Construction Order). The court
 noted that the parties “essentially agreed[]” upon the
 meaning of cavity and “both parties suggest inclusion of
 [not passing all the way through].” 

Id. at *9

. The court
 explained that unlike a tunnel that passes all the way
 through, the “cavity” does not pass all the way through the
 “first component” (e.g., lever 152 from Figure 13A because
 the cavity is bounded at one end by the rounded, upper por-
 tion of the lever 152). 

Id.

 The court also construed “sub-
 stantial amount” of the first bracket to mean “more than a
 majority” of the first bracket and “disposed within” to mean
 “placed inside of.” 

Id.

 at *4–8. Taken together, the cavity
 limitation was construed as “more than a majority of the
 first bracket is placed inside of a hollowed-out space (not
 passing all the way through) defined by the first compo-
 nent.” 

Id. at *10

.
    After claim construction, the parties exchanged their
 expert reports and filed cross-motions for summary
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 6                        LITTLE GIANT LADDER SYSTEMS, LLC v.
                                      TRICAM INDUSTRIES, INC.


 judgment. Summary Judgment Order, 

2024 WL 1332027

,
 at *1. Before addressing the summary judgment motions,
 the court granted Tricam’s motion to exclude the testimony
 of Little Giant’s expert, Mr. Smith, concerning infringe-
 ment of the cavity limitation for failing to apply the court’s
 construction. 

Id. at *22

. The court rejected Mr. Smith’s
 incorrect understanding that hollowed-out spaces un-
 bounded on both ends (e.g., a tunnel or a taco shell) can be
 the claimed cavity. 

Id.

 at *14–16.
      The district court then granted Tricam’s motion for
 summary judgment of noninfringement. 

Id. at *22

. It did
 so as to literal infringement because Little Giant’s sole ba-
 sis for literal infringement of the “cavity” limitation rested
 on Mr. Smith’s excluded opinion. 

Id. at *17

. The court ex-
 plained that the space in Tricam’s Speed Lock handle that
 Little Giant asserted as the cavity cannot satisfy the
 claimed cavity as properly construed, because that space is
 akin to a tunnel that passes all the way through. 

Id.

 at
 *16–17. As to infringement under the doctrine of equiva-
 lents, the court applied amendment-based estoppel, finding
 that Little Giant surrendered claim scope that encom-
 passes non-cavity structures concealing the majority of the
 bracket. 

Id. at *20

.
     Little Giant timely appealed. We have jurisdiction un-
 der 

28 U.S.C. § 1295

(a)(1).
                         DISCUSSION
     Little Giant appeals (1) the district court’s claim con-
 struction of “cavity,”4 (2) its exclusion of Mr. Smith’s in-
 fringement opinion, and (3) its summary judgment of




     4   Little Giant is not appealing construction of any
 other terms. See generally Appellant Br.; see also Appel-
 lant Reply Br. 23 n.9.
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                         7
 TRICAM INDUSTRIES, INC.


 noninfringement. See Appellant Br. 31–33. We address
 each in turn.
                    I. Claim Construction
     We review a district court’s claim construction de novo
 and its underlying factual determinations for clear error.
 See NexStep, Inc. v. Comcast Cable Commc'ns, LLC, 

119 F.4th 1355, 1364

 (Fed. Cir. 2024).
     Little Giant urges us to construe the claimed “cavity”
 to add a highly particularized meaning to the “does not
 pass all the way through” portion of the district court’s con-
 struction: “a hollowed-out space that doesn’t pass all the
 way through in such a way that (i.e., in enough directions)
 more than a majority of the bracket can be hidden or con-
 cealed inside of that space.” Appellant Br. 33 (emphasis
 omitted). Little Giant argues that the district court’s con-
 struction “contradicts the plain meaning of ‘cavity’ and
 stands in direct conflict with the intrinsic record.” Id. at
 35. Alternatively, in its reply brief, Little Giant suggests
 “cavity” should simply be “a hollowed-out space.” Appel-
 lant Reply Br. 12.
     We first address the inclusion of the adjectival phrase
 “not passing all the way through.” Little Giant proposes to
 remove this adjectival phrase, arguing that the plain and
 ordinary meaning of “cavity” is broad. Appellant Reply Br.
 2. We reject Little Giant’s invitation to rewrite the con-
 struction, because the district court adopted the parties’
 “essentially agreed-upon” construction of the claimed “cav-
 ity” as a “hollowed-out space (not passing all the way
 through).”5 Claim Construction Order, 

2022 WL 2287048

,


     5  As part of its proposed construction of a larger
 phrase, Little Giant argued that “cavity” should mean “a
 hollowed out space (not passing all the way through).”
 Claim Construction Order, 

2022 WL 2287048

, at *4.
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 8                        LITTLE GIANT LADDER SYSTEMS, LLC v.
                                      TRICAM INDUSTRIES, INC.


 at *8–10. Little Giant never argued below or in its opening
 brief against the inclusion of the phrase “not passing all the
 way through.” Instead, the opposite is true; it had consist-
 ently maintained the inclusion of that phrase. J.A. 270,
 1418–19, 2757; Appellant Br. 51–52. For this reason, we
 find Little Giant’s reply brief position forfeited. See Wash
 World Inc. v. Belanger Inc., 

131 F.4th 1360

, 1368–69 (Fed.
 Cir. 2025); see TVIIM, LLC v. McAfee, Inc., 

851 F.3d 1356, 1363

 (Fed. Cir. 2017) (“[A] party may not introduce new
 claim construction arguments on appeal or alter the scope
 of the claim construction positions it took below.”) (citation
 omitted). Accordingly, Little Giant is bound by the lan-
 guage “not passing all the way through.”
      Next, we address how to best read this adjectival
 phrase.6 The origin of this phrase plainly comes from the
 Notice of Allowance, where the patent examiner used this
 exact phrase to articulate his conception of the claimed cav-
 ity. J.A. 338. We understand that although Little Giant
 argued for this phrase to be part of the construction of “cav-
 ity,” it also below, as a gloss to that construction, explained
 its particularized understanding of that phrase, which it
 now asks this Court to formally incorporate into the claim
 construction. See J.A. 268–70, 1417–19, 2741–42. Little
 Giant explains that there was a disagreement about what
 this language means. See Oral Arg. at 06:52 – 07:15; see
 also J.A. 4988. In essence, Little Giant argues that this



 Tricam’s proposed construction for “cavity” was essentially
 the same: “a hollowed-out space in a mass that does not
 pass all the way through.” 

Id.

 (emphasis added). Tricam
 admits that inclusion or exclusion of “in a mass” does not
 make a material difference. See Appellee Br. 14–15.
     6   During oral argument, Little Giant agreed that
 this is a fair characterization of the issue. Oral Arg. at
 02:36 – 03:05 (available at https://www.cafc.uscourts.gov/
 oral-arguments/24-2115_01082026.mp3).
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                         9
 TRICAM INDUSTRIES, INC.


 adjectival phrase needs a directional elaboration (“in
 enough directions”) and a concept of “hid[ing] or con-
 ceal[ing]” the bracket. See Appellant Br. 40, 49. To explain
 its position, Little Giant provides its diagrammatic depic-
 tions (shown below) of lever 152 from Figures 13A and 13B
 and also points to the examiner’s statement in the Notice
 of Allowance. 

Id.

 at 50 (citing J.A. 338).




 Appellant Br. 27 (Little Giant’s diagrammatic depictions).
      We disagree that the Notice of Allowance supports Lit-
 tle Giant’s proposed understanding of “not passing all the
 way through.” There, the examiner interpreted the
 claimed “cavity” as “a hollowed out space in a mass such as
 a cavity in a tooth, where the hollowed space doesn’t pass
 all the way through [as shown by the drawings in the in-
 stant invention] such that the first component would hide
 or cover more than a majority of the first bracket.” J.A. 338
 (alteration in original) (emphasis added). As the examiner
 noted, Figures 13A–B are instructive as to what he meant
 by “not passing all the way through.”
      Like the examiner, the district court relied on the in-
 struction of Figures 13A–B. The district court noted that
 when the handle/lever 152 is in the claimed “first rotational
 position” as shown in Figure 13A, “the hollowed-out space
 defined by the handle” is “bounded on one end by the
 rounded, upper portion of the handle, open on the other end
 of the handle, and blocked off on the underside by the plane
 of the rail.” Summary Judgment Order, 

2024 WL 1332027

,
 at *11 (emphasis added). Meaning, because one end of the
 handle is closed off against the rail, “in that configuration,
 the hollowed-out space does not pass all the way through
 [the handle] in any direction.”          

Id.

   Little Giant’s
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 10                       LITTLE GIANT LADDER SYSTEMS, LLC v.
                                      TRICAM INDUSTRIES, INC.


 diagrammatic depictions improperly divorce the handle
 from the rest of the locking mechanism portrayed in the
 figures and fails to account for what claim 1 requires,
 namely the existence of the rail in relation to the bracket
 and the handle.7 See Appellant Br. 27. Therefore, we reject
 Little Giant’s argument that “not passing all the way
 through” needs a directional elaboration.
      We also find Little Giant’s argument for “hidden or con-
 cealed” unpersuasive. Little Giant previously advocated
 for this construction under its proposed construction of the
 term “disposed within,” see J.A. 267, and it is not appealing
 the district court’s construction of that term, see Appellant
 Reply Br. 23 n.9. In any event, neither the examiner’s
 statement, the claims, nor the specification support Little
 Giant’s assertion. See Summary Judgment Order, 

2024 WL 1332027

, at *4; see also Claim Construction Order,
 

2022 WL 2287048

, at *9. Accordingly, we affirm the dis-
 trict court’s claim construction.
      II. Exclusion of Mr. Smith’s Infringement Opinion
     We review a district court’s exclusion of expert testi-
 mony under the law of the regional circuit, here the Eighth
 Circuit. Sport Dimension, Inc. v. Coleman Co., 

820 F.3d 1316, 1323

 (Fed. Cir. 2016). The Eighth Circuit reviews
 the exclusion of an expert’s testimony “under the



      7  We reject Little Giant’s argument that the district
 court imported limitations from Figures 13A–B. See Ap-
 pellant Br. 45–51. The district court referred to those fig-
 ures to explain why it rejected Little Giant’s partial
 depiction of the figures’ locking mechanism. See Summary
 Judgment Order, 

2024 WL 1332027

, at *11. In any event,
 the district court’s reference to the figures was entirely con-
 sistent with the examiner’s reliance on those figures to il-
 lustrate his meaning of “doesn’t pass all the way through.”
 J.A. 338.
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                        11
 TRICAM INDUSTRIES, INC.


 deferential abuse of discretion standard and will not re-
 verse unless the district court’s ruling is ‘manifestly erro-
 neous.’” Bliv, Inc. v. Charter Oak Fire Ins. Co., 

159 F.4th 539

, 542 (8th Cir. 2025) (citation omitted).
     The district court excluded the testimony of Little Gi-
 ant’s expert, Mr. Smith, concerning his opinion that
 Tricam’s handle on its Speed Lock (shown below) literally
 meets the cavity limitation. Summary Judgment Order,
 

2024 WL 1332027

, at *16; J.A. 4544 ¶ 29. According to
 Mr. Smith, as shown below, the area under the black han-
 dle occupied by the purple bracket constitutes a “cavity”
 because that area is a hollowed-out space passing all the
 way through in at least one direction but not in every other
 direction. 

Id.

 See 

id.

 (Tricam’s Speed Lock, annotated).
     Little Giant argues that the exclusion of Mr. Smith’s
 infringement opinion was erroneous because the district
 court erred in construing the claimed “cavity.” See Appel-
 lant Br. 52, 54. Little Giant’s argument fails because we
 find no error in the district court’s construction.
      We also see no error in the district court’s finding that
 Mr. Smith contradicted the court’s construction by “essen-
 tially reconstru[ing] the cavity limitation to mean any hol-
 lowed-out space that does not pass through in every
 direction.” Summary Judgment Order, 

2024 WL 1332027

,
 at *15 (emphasis added). Although the claim construction
 explicitly stated that “the claimed cavity does not include
 hollowed-out spaces that are unbounded on both ends”
 such as a “tunnel” or a “taco shell,” Mr. Smith opined that
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 12                      LITTLE GIANT LADDER SYSTEMS, LLC v.
                                     TRICAM INDUSTRIES, INC.


 a hollowed-out space that passes all the way through two
 unbounded ends would literally have the claimed cavity.
 Id.; see also J.A. 4388, 4989–90. Accordingly, the district
 court did not abuse its discretion by excluding Mr. Smith’s
 infringement opinion “based on a claim construction that is
 materially different from the construction adopted by the
 parties and the court.” Treehouse Avatar LLC v. Valve
 Corp., 

54 F.4th 709, 715

 (Fed. Cir. 2022).
                  III. Summary Judgment
     We review a district court’s grant of summary judg-
 ment under the law of the regional circuit, here the Eighth
 Circuit. Niazi Licensing Corp. v. St. Jude Med. S.C., Inc.,
 

30 F.4th 1339, 1350

 (Fed. Cir. 2022). The Eighth Circuit
 reviews a grant of summary judgment de novo. 

Id.

 (citing
 Wilson v. Spain, 

209 F.3d 713, 716

 (8th Cir. 2000)). Sum-
 mary judgment is appropriate “if the movant shows that
 there is no genuine dispute as to any material fact and the
 movant is entitled to judgment as a matter of law.” FED.
 R. CIV. P. 56(a).
     The district court granted summary judgment of non-
 infringement, determining that (1) no reasonable jury
 could conclude that Tricam’s Speed Lock literally infringes
 the cavity limitation and (2) amendment-based estoppel
 precludes Little Giant from relying on the doctrine of
 equivalents.    Summary Judgment Order, 

2024 WL 1332027

, at *22.
     Little Giant offers two arguments: (1) because the
 claim construction of “cavity” was erroneous, the summary
 judgment should be vacated, and (2) even if the claim con-
 struction was correct, the district court erroneously applied
 amendment-based estoppel. See Appellant Br. 55–64. We
 find both unpersuasive.
                 A. No Literal Infringement
     We begin with the district court’s summary judgment
 of no literal infringement. Little Giant’s sole argument
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                          13
 TRICAM INDUSTRIES, INC.


 requires prevailing on the “cavity” claim construction. See
 Appellant Br. 57 (arguing that “Mr. Smith’s expert opin-
 ions raise a genuine dispute of fact regarding the presence
 of the ‘cavity’ limitation in the accused [product]” “under
 the proper construction of ‘cavity,’ as set forth in Mr.
 Smith’s reports”). Because we affirm the district court’s
 construction of the claimed “cavity,” the summary judg-
 ment of no literal infringement stands.
      In any event, the district court did not err in its literal
 infringement analysis. The cavity limitation requires that
 “more than a majority of the first bracket is placed inside
 of” a cavity. Claim Construction Order, 

2022 WL 2287048

,
 at *10 (emphasis added). As depicted below, the Speed
 Lock undisputedly has five hollowed-out spaces within its
 handle that do not pass all the way through, each space
 corresponding to the claimed cavity.8 See Summary Judg-
 ment Order, 

2024 WL 1332027

, at *2–3. However, it is also
 undisputed that only 20% of the volume of the bracket is
 placed inside of these five cavities; therefore, the cavity
 limitation was not met. See 

id. at *16

. Little Giant as-
 serted that the Speed Lock handle’s wing space is also the
 claimed cavity, thereby satisfying the claim limitation
 “more than a majority of the first bracket.” 

Id. at *16

; see
 also J.A. 2744. The district court properly rejected Little
 Giant’s assertion because it relied on Mr. Smith’s excluded
 opinion that a tunnel or taco-shaped structure, which
 passes all the way through, satisfies the cavity limitation.
 

Id. at *17

 (further noting that “Little Giant identifies no
 other evidence” to support literal infringement).




     8   Tricam conceded that Speed Lock has center and
 outer cavities as depicted in the right figure. J.A. 48. The
 parties, however, disputed whether the wing space meets
 the claimed “cavity.” J.A. 51, 2744 (defining the wing
 space).
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 14                       LITTLE GIANT LADDER SYSTEMS, LLC v.
                                      TRICAM INDUSTRIES, INC.


 Accordingly, we see no error in the district court’s summary
 judgment of no literal infringement.




 See Summary Judgment Order, 

2024 WL 1332027

, at *2–3
 (Tricam’s Speed Lock, alongside a labeled image of its un-
 derside); see also J.A. 2744.
      B. Preclusion under the Doctrine of Equivalents
     “Prosecution history estoppel applies as part of an in-
 fringement analysis to prevent a patentee from using the
 doctrine of equivalents to recapture subject matter surren-
 dered from the literal scope of a claim during prosecution.”
 Pharma Tech Sols., Inc. v. LifeScan, Inc., 

942 F.3d 1372, 1380

 (Fed. Cir. 2019) (citation omitted). The Supreme
 Court explained that a patentee’s “decision to narrow his
 claims through amendment may be presumed to be a gen-
 eral disclaimer of the territory between the original claim
 and the amended claim.” Festo Corp. v. Shoketsu Kinzoku
 Kogyo Kabushiki Co., 

535 U.S. 722, 740

 (2002). One of the
 ways the presumption may be overcome is if the patentee
 shows that “the rationale underlying the amendment may
 bear no more than a tangential relation to the equivalent
 in question” (tangential relation exception). 

Id.

 The tan-
 gential relation exception “focuses on the patentee’s objec-
 tively apparent reason for the narrowing amendment,”
 which “should be discernible from the prosecution history
 record.” Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki
 Co., 

344 F.3d 1359, 1369

 (Fed. Cir. 2003).
      Little Giant challenges the district court’s rejection of
 its theory under the doctrine of equivalents that “the wing
 space in the Speed Lock handle ‘performs the same
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 LITTLE GIANT LADDER SYSTEMS, LLC v.                         15
 TRICAM INDUSTRIES, INC.


 function as the claimed cavity by encompassing more than
 a majority of the bracket when in the first rotational posi-
 tion.’” Summary Judgment Order, 

2024 WL 1332027

, at
 *17. It argues that the district court erred in two regards:
 (1) the Festo presumption does not apply because the Speed
 Lock does not fall within the surrendered territory, and
 (2) even if the Speed Lock falls within the surrendered ter-
 ritory, the tangential relation exception rebuts that pre-
 sumption. See Appellant Br. 59–60.
      We reject both arguments. First, the district court did
 not err in its findings on the scope of the territory surren-
 dered. During the ’416 patent prosecution, the examiner
 rejected the claim language of “a substantial portion of the
 first bracket is concealed between the first rail and the first
 component” over a prior art reference 

U.S. Patent No. 2006

/0169539 (Grebinoski). J.A. 2931–33. In re-
 sponse, the applicant amended claim 1 to recite “the first
 bracket is disposed within a cavity defined by the first com-
 ponent,” which appears in the issued claim. J.A. 2943. In
 view of this narrowing amendment, we agree with the dis-
 trict court that the surrendered territory is between “de-
 signs where the bracket is concealed between the handle
 and the rails” and “where it is disposed within a cavity of
 the handle.” See Summary Judgment Order, 

2024 WL 1332027

, at *20. And the Speed Lock handle’s wing space
 does fall within this surrendered territory because there
 “the majority of the bracket is concealed between the han-
 dle and the rail simply because that concealment occurs by
 placing substantial portions of the bracket inside a space
 that is not a cavity.” 

Id.

     Second, the district court also did not err in determin-
 ing that the tangential relation exception does not apply.
 Little Giant argues that the amendment at issue was to
 overcome “handles that merely conceal part of the bracket
 outside the handle.” See Appellant Br. 59–60 (emphasis
 omitted). We disagree. Little Giant’s proposed tangential
 rationale is not objectively apparent from the prosecution
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 16                      LITTLE GIANT LADDER SYSTEMS, LLC v.
                                     TRICAM INDUSTRIES, INC.


 history. See generally J.A. 2908–52. This is because, as
 the district court found, “the difference between conceal-
 ment (or something being hidden between the handle and
 the rail) and being disposed within a cavity, was at the
 heart of the amendments to avoid Grebinoski.” Summary
 Judgment Order, 

2024 WL 1332027

, at *21. Accordingly,
 we hold that Little Giant has not met its burden of proving
 that the objectively apparent reason for the narrowing
 amendment was only tangentially related to the equiva-
 lent.
                        CONCLUSION
     We find none of Little Giant’s remaining arguments
 persuasive. For the foregoing reasons, we affirm.
                       AFFIRMED