AR-15 Pistol Buffer Tube (PBT) by Phase 5 Weapon Systems features our billet aluminum buffer tube, foam pad constructed of ultra-durable nitrile rubber, plus Mil-Spec end plate and castle nut. Buffer tube is compatible with Mil-Spec carbine buffer and spring, and the lower slot is machined to accept all Mil-Spec end plates and sling mounting accessories. Works with the SB Tactical Pistol Stabilizing Braces. Nice snug fit to insure no unwanted brace movement during pistol operation. Also allowing any desired brace position with zero restrictions, all the way forward or as far back on the tube as you would like. *Note- Compatible with SB Tactical Braces that accept round tubes. Not compatible with adjustable braces (ie: SBA3, SBA4, PDW). Includes- Pistol Buffer Tube, Castle Nut, End Plate, Foam Pad, Carbine Buffer and Phase 5 Enhanced Buffer Spring.