Kit includes everything for a new .223 AR15 Rifle build or to convert your current AR15 Carbine to a A2 AR15 Rifle buffer tube recoil system. - Note: Converting a carbine length gas system to use a A2 Rifle length buffer system may cause reliability issues. - Kit includes: - (1) A2 Rifle Buttstock Extension Tube - Material: 6061-T6 Aluminum - Finish: Hardcoat Anodized Black - (1) Standard .223 Rifle Buttstock Buffer Spring - (1) Standard Rifle Buffer Body Assembly