Cobalt Kinetics CK-Pro Built Upper Receiver Group 16in Barrel 5.56x45mm NATO Black. All CK-Pro URG s are expertly built by our gunsmith staff and come with 1 Duramag. Built URG s are test-fired for function before leaving out the door to the customer. Upgrade your current platform RUN COBALT the Built line includes a charging handle and bolt carrier group Specifications for Cobalt Kinetics CK-Pro Built Upper Receiver Group: Manufacturer: Cobalt Kinetics Caliber: 5.56x45mm NATO Muzzle Device: Flash Hider Gun Type: Rifle Condition: New Features of Cobalt Kinetics CK-Pro Built Upper Receiver Group:Cutting edge innovation.Military grade durability.Match grade precision.Uncompromising functionality. Package Contents: Cobalt Kinetics CK-Pro Built Upper Receiver Group Cobalt Kinetics CK-PRO-URG-556-16-B-BLK: CK-Pro Built Upper Receiver Group 16in Barrel 5.56x45mm NATO Black