The QD (Quick Detach) swivel system is an ingenious small attachment device that clicks into a specially shaped opening found on the front hand-guards and stocks on many modern rifles. It is quickly released by simply pressing on the center button.
Made of steel with black anodize surface and steel ball bearings.
Intended for the M40A3 spring operated sniper rifle ref. 17993 and 50098, but will fit other guns.