Quanzhou Fengze v. AB Mill: Pilates Board Patent Dismissed With Prejudice
Quanzhou Fengze Daxiong net tech, a Chinese fitness accessory manufacturer, filed a declaratory judgment action against AB Mill, LLC over US11491364B2 — a patent covering a Pilates push-up board elbow support accessory. The case resolved by stipulated dismissal with prejudice after 193 days, with each party bearing its own costs.
A Declaratory Judgment Skirmish Over Fitness Equipment IP
On December 13, 2024, Quanzhou Fengze Daxiong net tech Co., LTD., a Chinese net-tech and consumer goods company, filed a declaratory judgment action against AB Mill, LLC in the U.S. District Court for Massachusetts before Judge Mark G. Mastroianni. The dispute centered on US11491364B2, a U.S. patent covering a Pilates push-up board marketed as an elbow support accessory — a product category with growing commercial competition as fitness hardware proliferates on e-commerce platforms.
The case ended on June 24, 2025, via a stipulated dismissal with prejudice pursuant to Rule 41(a)(1)(ii), jointly filed by counsel for both parties. Each side agreed to waive all appellate rights and to bear its own costs, attorneys’ fees, and expenses. Dismissal with prejudice is a final adjudication on the merits as a matter of law — meaning Quanzhou Fengze cannot refile the same declaratory judgment claims, and AB Mill retains the patent but cannot pursue the same claims in this forum against this plaintiff.
A resolution at 193 days — before typical claim construction proceedings — suggests the parties likely reached a commercial understanding outside the courtroom, though the public record is silent on any licensing terms or settlement payment. The mutual cost-bearing and waiver of appeal rights is consistent with a negotiated resolution rather than a capitulation by either side. What drove the resolution, and whether Quanzhou Fengze secured any license or freedom-to-operate assurance, remains undisclosed.
Filing to Dismissed with Prejudice in 193 days
193-day lifespan — resolved before substantive motion practice typically concludes
Dismissed with prejudice: what the stipulated exit means for both parties
Rule 41(a)(1)(ii) dismissal with prejudice — a permanent close
A Rule 41(a)(1)(ii) stipulated dismissal with prejudice requires agreement of all parties who have appeared. Unlike a voluntary dismissal without prejudice, this mechanism is a final adjudication on the merits — the same claims cannot be reasserted in any subsequent action. Both parties also expressly waived all appellate rights, making this termination fully final with no avenue for review.
Permanent — no refilingQuanzhou Fengze loses its declaratory judgment vehicle — permanently
As the party seeking a declaration of non-infringement or invalidity, Quanzhou Fengze’s claims are extinguished with prejudice. The company cannot refile this declaratory action. However, the mutual cost-bearing and early resolution suggest the outcome may reflect a negotiated commercial resolution — potentially including a license or covenant not to sue — though the public record does not confirm this. Any such agreement would have been reached privately.
DJ claims extinguishedAB Mill retains patent — but this forum closes permanently too
AB Mill, LLC preserves US11491364B2 intact — no invalidity or non-infringement declaration was entered. The patent’s enforceability is unchanged. However, AB Mill also agreed to dismiss with prejudice and bear its own costs, which is consistent with having reached an accommodation with Quanzhou Fengze. AB Mill cannot revive infringement claims against this plaintiff arising from the same conduct that prompted the DJ action in this court.
Patent survives; forum closedE-commerce fitness IP: early exits signal enforcement pressure on Chinese sellers
Declaratory judgment actions by Chinese manufacturers against U.S. patent holders are increasingly common in the fitness and consumer goods e-commerce space, often triggered by Amazon seller threats or platform takedown notices. Early resolution — as seen here — typically signals either a licensing deal or a deterrence outcome. Other sellers of Pilates push-up board accessories should treat US11491364B2 as an active enforcement risk and conduct FTO analysis before listing products in the U.S. market.
Active enforcement riskFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Quanzhou Fengze Daxiong net tech Co., LTD. | Company | Chinese fitness accessories manufacturer — declaratory judgment seeker over US11491364B2Search in Eureka ↗ |
| Defendant | AB MILL, LLC | Company | AB Mill, LLC — U.S. entity asserting rights under Pilates push-up board elbow support patentSearch in Eureka ↗ |
| Plaintiff counsel | Luca L. Hickman | Attorney | Counsel for Quanzhou Fengze Daxiong net tech Co., LTD.Search in Eureka ↗ |
| Plaintiff counsel | Trevor James Brown | Attorney | Counsel for Quanzhou Fengze Daxiong net tech Co., LTD.Search in Eureka ↗ |
| Plaintiff counsel | Xionghui Murong | Attorney | Counsel for Quanzhou Fengze Daxiong net tech Co., LTD.Search in Eureka ↗ |
| Plaintiff law firm | Dinsmore & Shohl LLP | Law Firm | Representing Quanzhou Fengze Daxiong net tech Co., LTD.Search in Eureka ↗ |
| Plaintiff law firm | Glacier Law LLP | Law Firm | Representing Quanzhou Fengze Daxiong net tech Co., LTD.Search in Eureka ↗ |
| Defendant counsel | Justin S. Weddle | Attorney | Counsel for AB MILL, LLCSearch in Eureka ↗ |
| Defendant counsel | Michael H. Domesick | Attorney | Counsel for AB MILL, LLCSearch in Eureka ↗ |
| Defendant law firm | Weddle Law PLLC | Law Firm | Representing AB MILL, LLCSearch in Eureka ↗ |
| Presiding judge | Judge Mark G. Mastroianni | Judge | Massachusetts District CourtSearch in Eureka ↗ |
Official order — verbatim text
The stipulated dismissal is drafted in precise, mutual terms: both parties agreed through counsel, invoked Rule 41(a)(1)(ii), and expressly waived appellate rights. The phrasing ‘all claims and causes of action set forth therein’ confirms no residual claim survives in this action. The mutual cost-bearing clause — rather than a fee award to either side — is commercially neutral on its face, though it offers no insight into whether a private licensing arrangement was reached concurrently. The patent itself emerges legally unscathed.
US11491364B2 — Pilates Push-up Board Elbow Support Accessory
US11491364B2 (application number US16/368962) protects a Pilates push-up board marketed as an elbow support accessory — a consumer fitness product designed to support arm positioning during push-up and Pilates exercises. The patent falls within the consumer fitness equipment segment, a category that has seen significant IP activity as product commoditization on e-commerce platforms drives rights holders to assert patents defensively against overseas manufacturers entering U.S. distribution channels.
For AB Mill, US11491364B2 represents an enforcement asset capable of generating licensing pressure on Chinese manufacturers and e-commerce sellers offering competing Pilates board accessories. The fact that a Chinese manufacturer sought declaratory relief — rather than waiting for a lawsuit — suggests the patent was being actively used as a commercial lever, likely through demand letters or platform takedown notices. The patent survived this litigation without any adverse validity or infringement finding, leaving it fully available for future enforcement against third parties.
Should your team run an FTO against US11491364B2?
Any company manufacturing, importing, distributing, or selling Pilates push-up boards or elbow support fitness accessories in the United States should treat US11491364B2 as a live enforcement risk. This case demonstrates that the patent holder is willing to assert rights against Chinese-origin products entering U.S. commerce — and that the patent survived the litigation legally intact. Sellers active on Amazon or other U.S. e-commerce platforms in this product category face the highest immediate exposure.
PatSnap Eureka’s FTO Search Agent allows R&D and product teams to map their push-up board or elbow support accessory designs against the claim scope of US11491364B2 in minutes. Eureka surfaces related prior art, identifies claim elements most likely to be contested, and flags design-around opportunities — enabling legal and product teams to make evidence-based clearance decisions before market entry or platform listing.
Run a freedom-to-operate analysis on US11491364B2 to assess your product’s exposure
Run FTO in Eureka →Similar patent cases: fitness equipment DJ actions in U.S. district courts
Cases below involve declaratory judgment actions over consumer fitness equipment patents in U.S. district courts — the same legal posture and technology segment as this Massachusetts case.
What this case signals for the fitness equipment IP landscape
Fast-resolved DJ actions in fitness accessories suggest patent holders are actively policing e-commerce channels — and extracting value before trial.
DJ filings by Chinese sellers are a bellwether for e-commerce patent pressure
When Chinese manufacturers file declaratory judgment actions in U.S. district courts, it typically signals a credible enforcement threat — a cease-and-desist letter, a platform takedown notice, or a demand letter. This case’s trajectory is consistent with that pattern. Competitors in the Pilates and push-up board accessory segment should audit their exposure to US11491364B2 proactively.
With-prejudice exits before claim construction carry strategic ambiguity
A dismissal with prejudice before any substantive ruling leaves the patent’s validity and scope legally untested. AB Mill retains a fully enforceable patent with no adverse court findings. For downstream sellers and distributors, this means the patent presents an unresolved legal risk — neither confirmed valid nor invalidated by the court proceedings.
Quanzhou v AB — key questions answered
The case was dismissed with prejudice by stipulation of both parties on June 24, 2025, pursuant to Rule 41(a)(1)(ii). Each party agreed to bear its own costs, attorneys’ fees, and expenses, and waived all appellate rights. No court ruling on the merits of infringement or validity was issued.
The patent at issue was US11491364B2 (application number US16/368962), covering a Pilates push-up board marketed as an elbow support accessory. The product involved is described in the case as the ‘Elbow Support Accessories.’ The patent remains enforceable — no invalidity finding was made.
Dismissal with prejudice constitutes a final adjudication on the merits under U.S. federal procedure. Quanzhou Fengze cannot refile the same declaratory judgment claims against AB Mill in any court. The company also waived all appellate rights, making the termination fully final.
Yes. The stipulated dismissal did not include any court finding on the validity or infringement scope of US11491364B2. The patent emerged from the litigation legally unaffected and remains available for enforcement against third parties. Sellers of competing Pilates board products in the U.S. should conduct freedom-to-operate analysis.
Declaratory judgment actions allow a party facing credible patent enforcement threats — such as cease-and-desist letters, demand letters, or Amazon platform takedown notices — to choose the forum and timeline for resolution. By filing first, Quanzhou Fengze sought to resolve uncertainty over US11491364B2 on its own terms. The early with-prejudice settlement suggests the strategy may have produced a negotiated outcome, though the terms remain confidential.
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