Dark Storm Industries DS-15 Complete Upper 16" Lightning 5.56 Threaded Black 5.56. 750 Micro Gas Block and Carbine Gas System. Specifications for Dark Storm Industries DS-15 16" Lightning 5.56 Upper Receiver: Manufacturer: Dark Storm Industries Caliber: 5.56x45mm NATO Barrel Length: 16 in Barrel Twist Rate: 1-9 Muzzle Device: Linear Compensator Finish: Anodized Color: Black Gun Rail: M-LOK Gun Model: AR-15 Condition: New Magazine Included: No Mount Type: Picatinny Features of Dark Storm Industries DS-15 16" Lightning 5.56 Upper Receiver DSI Forged Upper Receiver w/ Forward Assit and Ejection Port Cover NiB M16 Bolt Carrier Group Spec Ops Gen 2 Charging Handle DSI Ultralight M-Lok 13" Forearm Micro Gas Block and Carbine Gas System Stainless Steel 16" 5.56 1:9 Barrel w/ Stainless Steel Competition Compensator Package Contents: Dark Storm Industries DS-15 16" Lightning 5.56 Upper Receiver No What firearm models does the manufacturer say Dark Storm Industries DS-15 16" Lightning 5.56 Upper Receiver is compatible with? The manufacturer says that Dark Storm Industries DS-15 16" Lightning 5.56 Upper Receiver is compatible with AR-15Dark Storm Industries DSI-UC5-LGT-T5-BLK: DS-15 Complete Upper 16" Lightning 5.56 Threaded Black 5.56