The X Products R.O.C. (Rapid Operation Carbine) Stock is the most adapted PDW stock design available in the smallest package. Ergonomic, easy to use and designed for a low profile, compact platform. The X Products ROC Stock set will fit on any Mil-Spec AR-15/M4 & HKMR556, HK 416 lower receiver. Tested and designed to be used with nearly ALL commercial and LE/Mil ammunition types. Easy to install and durable. Its 5 adjustment points give the shooter maximum versatility. To top it off, the R.O.C. Stock does NOT require a proprietary bolt carrier or special components. Use a true drop on PDW stock set solution for your HK 416C or AR/M4 PDW project. Made 100% in the USA. Includes stock and assembly pieces, DOES NOT INCLUDE RIFLE