Windham Weaponry Multi-Caliber Bug-Out Bag, Semi-automatic, Multi-Caliber System, RMCS Lower Receiver with .223 & 9mmInterchangeable Magazine Wells, RMCS Upper Receiver with Fixed Quad Rail Forend and Barrel Locking Mechanism, 2 Barrels: 16" 223 Rem/556NATO M4 Profile, Chrome Lined with M4 Feed Ramps & a 16" 9mm Barrel with Melonite Finish with a 9mm Blowback Bolt and a 9mm Buffer, 22LR Bolt Assembly, 22LR Magazine, Mission First Tactical Minimalist Stock, Includes Compartmented Backpack with Pouches for All Components RMCS-BOB