This AR-15/M4 Carbine Collapsible Buttstock is a drop-in replacement buttstock for the AR15/M16 using a Carbine Mil-Spec Receiver Extension (Buffer Tube) such as Colt, Armalite, S&W, LMT, and most other AR platforms. This M4/AR-15 carbine stock is a 6-position collapsible stock that is constructed of heavy duty polymer with a sling swivel and slot to attach a sling. It has a quick-adjustable lever lock for making adjustments fast and easy on your Mil-Spec buffer tube.