Shenzhen Stronger Technology Co Ltd v. Travel Caddy Inc

I. Executive Summary and Procedural Information

• Case Name: Shenzhen Stronger Technology Co., Ltd. v. Travel Caddy, Inc.
• Parties & Counsel:
  • Plaintiff: Shenzhen Stronger Technology Co., Ltd. (People's Republic of China)
  • Defendant: Travel Caddy, Inc. (Illinois)
  • Plaintiff’s Counsel: Glacier Law LLP
• Case Identification: 1:26-cv-01307, N.D. Ill., 02/04/2026
• Venue Allegations: Venue is asserted as proper in the Northern District of Illinois because the Defendant, an Illinois corporation with its principal place of business in Franklin Park, resides in the district.
• Core Dispute: Plaintiff seeks a declaratory judgment that its zipper pull tabs do not infringe Defendant’s utility and design patents, following an accusation of infringement made by Defendant through Amazon's intellectual property complaint process.
• Technical Context: The technology relates to security features for zippers on luggage and personal bags, specifically interlocking pull tabs designed to prevent unauthorized access while maintaining aesthetic and functional appeal.
• Key Procedural History: The lawsuit was initiated in response to Defendant’s January 29, 2026 accusation of patent infringement against Plaintiff's products via Amazon's IP complaint system, which created the "actual controversy" necessary for a declaratory judgment action.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Design Patent No. D820,152 S - "Zipper Pull Tab"

• Patent Identification: U.S. Design Patent No. D820152 S, “Zipper Pull Tab,” issued June 12, 2018.

The Invention Explained

• Problem Addressed: The patent does not explicitly state a problem but addresses the general need for novel ornamental designs in the field of zipper hardware.
• The Patented Solution: The patent claims the specific ornamental design for a zipper pull tab as depicted in its figures (D’152 Patent, FIGS. 1-8). The design features a generally rectangular body with a carabiner-style hook at one end and a loop for attachment at the other, characterized by specific surface contours and proportions.
• Technical Importance: The patent protects the unique aesthetic appearance of a functional item, distinguishing it from other designs in the marketplace.

Key Claims at a Glance

• The patent contains a single claim for "the ornamental design for a zipper pull tab, as shown and described" D’152 Patent, claim
• The claim covers the visual appearance illustrated in Figures 1-8, with broken lines indicating unclaimed environmental subject matter.

U.S. Patent No. 12,220,026 B2 - "Interlocking Zipper Pull Tabs and Fastening System"

• Patent Identification: U.S. Patent No. 12,220,026 B2, “Interlocking Zipper Pull Tabs and Fastening System,” issued February 11, 2025.

The Invention Explained

• Problem Addressed: The patent’s background describes prior art zipper locks, such as combination or key locks, as "impractical and unsuitable" for daily-use bags like purses and briefcases due to aesthetic and functional drawbacks (ʼ026 Patent, col. 1:45-54). Other interlocking designs are described as prone to snagging or failure '026 Patent, col. 1:55-67
• The Patented Solution: The invention is a fastening system, typically involving two zipper pulls, that can interlock with each other for security '026 Patent, abstract A first pull tab incorporates a hook and a moveable gate, similar to a carabiner, which can lock onto a post integrated into a second pull tab ʼ026 Patent, FIG. 15 This design allows two zippers to be secured together without an external padlock, maintaining a flat profile against the bag to reduce snagging ʼ026 Patent, col. 2:10-19
• Technical Importance: The technology provides an integrated security solution for zippers that aims to be more convenient and aesthetically pleasing than traditional padlocks, making it suitable for fashion-oriented bags and luggage.

Key Claims at a Glance

• The complaint asserts non-infringement of independent claims 1, 11, and 18 Compl. ¶35
• Independent claim 1 includes the following essential elements:
  • A flat base with a first thickness and a first recess extending into the base from a second side.
  • A hook integrally formed with and extending from the base, comprising an elongated rectilinear portion and a C-shaped curvature.
  • A moveable gate pivotably coupled inside the first recess.
  • A C-shaped coupling extending from a first side of the base, having a thickness that tapers according to a specified ratio (between 4:1 and 2:1).
• The complaint notes that dependent claims are also not infringed because they incorporate all limitations of the independent claims from which they depend Compl. ¶39

III. The Accused Instrumentality

Product Identification

• The accused products are "high-quality zipper pull tabs" sold by Plaintiff Shenzhen Stronger Technology Co., Ltd. through Amazon.com Compl. ¶¶4, 10 The complaint identifies specific Amazon Standard Identification Numbers (ASINs) for the products at issue Compl. ¶11

Functionality and Market Context

• The complaint describes the accused products simply as "zipper pull tabs" Compl. ¶10 The core of the non-infringement argument is that these tabs lack specific structural features recited in the asserted patents Compl. ¶¶36-38 The products are marketed and sold to customers in the United States via Amazon, and the dispute arose directly from Defendant's use of Amazon's intellectual property complaint process, indicating the commercial significance of this online marketplace Compl. ¶¶10, 12
  No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

This is a declaratory judgment action where the Plaintiff alleges non-infringement. The complaint references comparison exhibits that were not provided; therefore, the non-infringement theories are summarized below in prose.

• D’152 Patent (Design Patent):
  Plaintiff asserts that its accused products do not infringe the '152 Patent because their overall visual impression is not "substantially the same" as the claimed design Compl. ¶28 The complaint argues that an ordinary observer familiar with prior art zipper pulls would not be deceived, pointing to alleged material differences in the accused product's "(i) the left-end silhouette and transition geometry, (ii) the shoulder geometry, (iii) the right-end termination geometry, and (iv) the ring-to-base relationship in the central region" Compl. ¶29

• ’026 Patent (Utility Patent):
  Plaintiff asserts that its accused products do not infringe independent claims 1, 11, and 18 of the ’026 Patent, either literally or under the doctrine of equivalents Compl. ¶¶34-35 The complaint specifically identifies several claim limitations that the accused products allegedly do not meet, including:

  • A "flat base" having "a first recess extending into the base from the second side" Compl. ¶36
  • A "moveable gate 'pivotably coupled inside' such a claimed recess" Compl. ¶36
  • A "C-shaped coupling" with the claimed tapering thickness profile and ratio Compl. ¶37
  • For claim 11, "a grip integrally formed with the moveable gate" Compl. ¶38

• Identified Points of Contention:

  • Scope Questions: For the ’026 Patent, a central question will be how key structural terms like "recess," "moveable gate," and "pivotably coupled inside" are construed. The dispute will likely focus on whether the accused product's mechanism, if any, for opening and closing falls within the scope of these claim terms as defined by the patent.
  • Technical Questions: A key factual question will be whether the accused products, upon physical inspection and measurement, possess the specific structures and dimensional ratios required by the claims of the '026 Patent, particularly the tapering thickness ratio of the "C-shaped coupling." For the D'152 Patent, the dispute is a holistic visual comparison, turning on whether the alleged geometric differences are significant enough to create a distinct overall appearance.

V. Key Claim Terms for Construction

• The Term: "moveable gate ... pivotably coupled inside the [first] recess" ’026 Patent, claim 1

• Context and Importance: This term is central to the invention's carabiner-like locking mechanism. Plaintiff specifically alleges its products lack a gate "pivotably coupled inside" a recess, making the construction of this phrase critical to the infringement analysis Compl. ¶36

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification describes the gate as "pivotable or otherwise moveable transversely (laterally) within the cavity or recess" '026 Patent, col. 10:11-15, which may support a construction not strictly limited to a single type of pivot.
  • Evidence for a Narrower Interpretation: The preferred embodiment illustrated in the patent figures shows a specific pin coupling (170) that secures the gate within the recess to create a pivot point '026 Patent, FIG. 9; col. 10:7-11 A defendant may argue that "pivotably coupled inside" requires such an internal, pinned connection.

• The Term: "C-shaped coupling having a thickness tapering ... wherein a ratio of the first thickness to the second thickness is between 4:1 and 2:1" ’026 Patent, claim 1

• Context and Importance: This limitation defines a specific geometric and dimensional property of the part that attaches to the zipper slider. Plaintiff alleges its products do not have a coupling with the recited tapering profile and ratio Compl. ¶37

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: Practitioners may focus on this term because while the ratio appears precise, disputes can arise over the exact measurement points for the "first thickness" and "second thickness." The patent does not define these points with mathematical precision, leaving room for argument.
  • Evidence for a Narrower Interpretation: The specification provides specific examples of the tapering, such as from 4.7 mm down to 1.6 mm, yielding a ratio of approximately 3:1 '026 Patent, col. 11:11-15 The patent also describes this tapering as "functional, not merely aesthetic" '026 Patent, col. 11:15-18, which may suggest that the dimensional ratio is a strict and essential feature of the invention, not an approximation.

VI. Other Allegations

The complaint is for a declaratory judgment of non-infringement and does not contain allegations of indirect or willful infringement. This section is therefore not applicable.

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue for the '026 utility patent will be one of structural definition: Do the accused products contain a "recess" and a "gate" that is "pivotably coupled inside" that recess, as those terms would be construed from the patent’s specification and drawings, or do they employ a fundamentally different, non-infringing mechanism?
• A second critical question for the '026 patent will be one of dimensional compliance: Upon factual examination, do the accused products’ components, particularly the "C-shaped coupling," meet the specific, numerically-defined tapering and ratio limitations recited in the independent claims, or do they fall outside these precise boundaries?
• For the D'152 design patent, the central question is one of holistic visual comparison: Are the alleged differences in silhouette and geometry between the accused products and the patented design significant enough to create a different overall visual impression for an ordinary observer, thereby avoiding infringement?