The Cry Havoc Tactical QRB (Quick Release Barrel) 1 Pin Upper Receiver Takedown Kit for AR-15 style rifles or pistols. Change calibers in seconds! The QRB allows you to remove the barrel of your rifle or pistol quickly. No drilling or modifications needed! Fit your AR-15 Carbine or Pistol into a Backpack or Bugout Bag with ease. Perfect for discreet transport. Assemble and Fire in seconds, even in low light. Able to KEEP strong hand on grip - Nothing to Depress or twist with strong hand. Use gross motor skills to assemble due to two-piece gas system. No lining up tiny gas access hole with gas tube first! Able to use a wide range of Free Float Hand Guards for the Mfg: Cry Havoc Tactical Inc.