Transition piece and folding stock for the HK USC. this is a polymer rear stock and transition piece. The stock is modeled off of the factory stock. The rear but pad is removable for easy replacement if it is ever damaged. The transition piece attaches to the rear of the USC receiver with the two factory threaded screw. The threaded insert in the transition piece is made of stainless steel so that it is rust resistant and the stock screws have a solid satiable attachment point that will go the rounds. The stock block is designed to attach to a lower with a push pin. (Included)