Stag 15 Tactical uppers have a carbine-length gas system that is combined with a low-profile gas block, which provides reliability under any condition. The handguard provides an uninterrupted picatinny rail along the top which allows room for sights, optics and accessories the shooter may require. Specifications for Stag Arms AR-15 Tactical Left Hand Upper Receiver: Manufacturer: Stag Arms Barrel Twist Rate: 1-7 Finish: Anodized Fabric/Material: Metal Gas Block Journal Size-Diameter: .750 in Handguard Length: 13.5 in Attachment/Mount Type: Picatinny Gun Rail: Picatinny Gun Type: Rifle Gun Make: AR Platform Gun Model: AR-15 Included Accessories: Standard Condition: New Bolt Carrier Group Included: No Magazine Included: No Charging Handle Included: No Mount Type: Picatinny Hand: Left Package Contents: Stag Arms AR-15 Tactical Left Hand Upper Receiver