Dumbbell Seller Ningbo Haoyang Seeks a Declaration That Adjustable Dumbbell Patent 12,594,453 Is Invalid, Saying the Patent Owner Sued It and Then Dismissed.

The case is Ningbo Haoyang Jixie Gongju Youxian Gongsi v. Zhong, No. 1:26-cv-10573 (N.D. Ill.), filed September 1, 2026 and assigned to Judge Steven C. Seeger, with Magistrate Judge Jeannice W. Appenteng designated. The complaint describes the plaintiff as a company based in Ningbo, China, that sells adjustable weight dumbbells, sold as EQUIPRO dumbbells, through online retailers such as Amazon, and the defendant, Duoming Zhong, as an individual residing in Heyuan, China, who owns the '453 patent. Venue is pleaded under 28 U.S.C. 1391(c)(3). The plaintiff demands a jury.

The earlier suit

According to the complaint, Zhong filed a patent infringement complaint against the company in the Northern District of Illinois on June 24, 2026, No. 1:26-cv-07374, alleging that its products infringe the '453 patent, and voluntarily dismissed the case without prejudice on June 26, 2026. The complaint says the company still reasonably fears another suit because Zhong has refused to discuss settlement, and it relies on the earlier filing for personal jurisdiction.

The patent

U.S. Patent 12,594,453, titled Weight-Adjustable Dumbbell, issued April 7, 2026, and the face of the patent lists Zhong as the applicant. Claim 1 covers a dumbbell with a handle, main counterweight blocks at each end of the handle, and auxiliary counterweight blocks that attach to them, each block made of a shell and cover plate enclosing an iron plate. The blocks join through a spinning buckle on one block and a spinning slot on the other: a stop block on the buckle passes through a notch in the slot's stop edge and, once the buckle is turned, is held behind the edge so that the main and auxiliary blocks lock together as a whole.

Invalidity theories

The complaint alleges that the claims are anticipated or obvious over twelve references, including UK application GB2610854A, Chinese patents CN216824658U and CN212395719U, and U.S. Patent 12,102,866, which it describes as disclosing main and auxiliary counterweight blocks joined by rotating buckles and locking devices. It also alleges invalidity under 35 U.S.C. 101 and 112. It asks for a declaration that all claims of the '453 patent are invalid and for attorneys' fees and costs.

What to watch next

Judge Seeger set an initial status report deadline of November 16, 2026. Watch for service on Zhong, the defendant's answer or motion to dismiss, and any infringement counterclaim.