ALEXANDRIA, Va., June 16 -- United States Patent no. 12,303,735, issued on May 20.
"Internal toothed mechanism for weight-adjustable safety dumbbell" was invented by Liwen Fu (Shanghai).
According to the abstract* released by the U.S. Patent & Trademark Office: "Disclosed is an internal toothed mechanism for a weight-adjustable safety dumbbell comprising a rotating disc and a stopper, wherein a middle section of the stopper is provided with a clamping groove, and a top end of the stopper is provided with a mounting hole for mounting a reset spring, and wherein the clamping groove defines an upper end surface and a lower end surface which are arc-shaped, and a plurality of top ratchets are arranged on the upper end surface of the clamping ...