This Bravo Company Receiver Extension Buffer Tube 6-Position Mil-Spec Diameter Stock Hardware Kit contains all the necessary parts to mount your Mil-Spec dimension stock assembly to your lower receiver. Kit IncludesReceiver Extension - Mil-Spec, 6 position (machined from 7075T6)Receiver End PlateLock Nut (Castle) M4Carbine Action SpringCarbine Standard Buffer Assembly This kit is compatible with the plastic stocks from; BCM, VLTOR, LMT, Magpul CTR-M, Stag Arms, Colt