Phase 5 Weapon Systems HEX2C Hex-2 Buffer Tube Assembly Black Aluminum AR-Pistol PlatformThe Phase 5 Hex 2 is an AR type Buffer Tube that starts with a hexagonal shape and the rear most portion is round. This tube was specifically designed this way to utilize the SB Tactical Pistol Stabilizing Braces that can accept a 1. 2" round buffer tube (Not compatible with adjustable type braces like the SBA3 SBA4 PDW). The Hex 2 is a heavy duty USA certified 7075 T7 billet aluminum buffer tube with the versatility to use the 3. 5" Phase 5 nitrile