Aero Precision M4E1-T SM10.3 5 Complete Upper 5.56 x 45 12.5inch Government Carbine 1-7 Twist 1/2 x 28 Thread Anodized Black. The S-ONE line of handguards are designed with size and weight in mind providing the perfect addition to your lightweight build. Our proprietary ATLAS attachment system is a durable and dependable mounting platform maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards. Specifications for Aero Precision M4E1-T SM10.3 5.56 x 45 Complete Upper: Manufacturer: Aero Precision Caliber: 5.56x45mm NATO Overall Length: 26.5 in Barrel Length: 12.5 in Barrel Profile: Government Gas System Length: Carbine Length Barrel Twist Rate: 1-7 Threads per Inch: 1/2x28 Muzzle Device: A2 Flash Hider Gun Model: AR-15 Condition: New Fabric/Material: 7075 T6 Aluminum Gas Block Journal Size-Diameter: .750 in Handguard Length: 10.3 in Gun Rail: M-LOK Gun Make: AR Platform Barrel Material: 4150 CMV Steel Bolt Carrier Group Included: No Charging Handle Included: No Weight: 42 oz Magazine Included: No Mount Type: M-LOK Country of Origin: USA Features of Aero Precision M4E1-T SM10.3 5.56 x 45 Complete Upper New enhanced forging that gives the upper receiver a "billet look" New picatinny profile that blends seamlessly with our Enhanced Series Handguards M4 Feedramps .250 takedown pin holes Laser engraved T-marks Includes port door and forward assist installed This complete upper does not include BCG or Charging Handle. Package Contents: Aero Precision M4E1-T SM10.3 5.56 x 45 Complete Upper What firearm models does the manufacturer say Aero Precision M4E1-T SM10.3 5.56 x 45 Complete Upper is compatible with? The manufacturer suggests that Aero Precision M4E1-T SM10.3 5.56 x 45 Complete Upper is compatible with AR-15Aero Precision APAR700103M30: M4E1-T SM10.3 5 Complete Upper 5.56 x 45 12.5inch Government Carbine 1-7 Twist 1/2 x 28 Thread Anodized Black