The EXOS Defense Milspec Receiver Extension Kit is made by the same company that produces receiver extensions, rail systems, buffers, stocks, and other components for the US Department of Defense and numerous Defense Manufacturers. The 7075 T6 Aluminum receiver extension features six positions allowing for additional adjustments over the standard four position receiver extension. Milspec Hard-Anodized finish is applied to the same standards as military parts. The phosphate-protected castle nut and end plate secure the extension in place on any in-spec lower receiver. A milspec stainless steel action spring and CAR buffer operate smoothly on M4-style carbines.