Pair this 12.5 5.56mm BANSHEE upper group with the Mk4/standard AR15 lower group of your choice to create a compact AR pistol or SBR that blends maneuverability with carbine like ballistic performance. Available in six different Cerakote finishes all CMMG Upper Groups come complete with bolt carrier group and ZEROED accessories including: - ZEROED AR15 Polymer Dust Cover - ZEROED AR15 Ambi Charging Handle - ZEROED Linear Compensator 5.56mm - Platform: Mk4 - Caliber: 5.56mm 5.56x45mm - Operating System: Direct Impingement - Barrel Length: 12.5 - Barrel Twist: 1:7 - Barrel Contour: MR - Barrel Material: 4140CM SBN - Muzzle Device: CMMG ZEROED Linear Compensator - Muzzle Thread: 1/2 x 28 - Gas Port Location: Carbine - Gas Block: 0.750 Non-Adjustable - Upper Receiver: Billet 6061 T6 Aluminum - Hand Guard: CMMG EML11 M-LOK - Finish: Cerakote Standard - Charging Handle: CMMG ZEROED Ambi - Weight: 3.8 lbs - Length: 20.8