To fully maximize the usage of your Cry Havoc Tactical QRB (Quick Release Barrel) 2 Pin Upper Receiver Takedown kit for the AR-15 they offer these additional QRB 1 Pin Barrel Locking Plate Kits to allow you to swap different barrels on a single lower. What to switch up between a 16" barrel and a 20" barrel in seconds while holding within 1 MOA? This kit makes that happen. The QRB 2 Pin Barrel Locking Plate Kits can only be used on Barrels with a maximum outside diameter of 0.985"" and Free Float Hand Guards with a maximum width of 2.0"" Also the QRB will add 1.5"" to the length of your free-floating hand guard. To purchase the proper k Mfg: Cry Havoc Tactical Inc.