The BLACKHAWK Knoxx Axiom A-Frame Carbine Stock is a multifaceted upgrade for the AR platform. Available in four colors” it features a forward length of pull (LOP) adjustment cam for a custom fit when shouldered. An integrated fit-adjustment screw sets the level of play between the stock and receiver extension. Multiple integrated QD sling mounts offer a choice of transportation options. Fits Mil-Spec diameter receiver extension tubes.