APS Poly Fiber RS1 Type 1 Stock For M4 M16 Series AEG Rifles Airsoft BlackAPS Poly Fiber RS1 Type 1 Stock For M4 M16 Series AEG Rifles Airsoft Made out of Poly Fiber Collapsible stock designed for rifle that equipped with AEG buffer tube. It is made out of military grade Poly Fiber materials increase the durability of the stock As long as user pulls the trigger of the stock, it can move the stock forward or backward freely along the buffer tube. The back of the stock is made out of rubber, it provides comfort and reduce