Aero Precision M4E1-T PRO CHF M4 5.56mm 13.9 inch Complete Upper Receiver Hanson Mid Length 1-7 Twist A2 Birdcage Anodized Black. The MOD 4 handguard seamlessly blends robust construction with an ergonomic form factor ensuring no compromises between the two. Machined from 6061-T6 aluminum the handguard is engineered with a focus on stiffness to drastically reduce deflection under load. It attaches to the upper receiver via a steel barrel nut which also serves to significantly reduce point-of-impact shift when using an infrared laser aiming device under load. A 7 sided M-LOK interface allows the user to customize their handguard to their exact specifications and needs. Lastly each of the 4 QD sockets on the MOD 4 utilize a steel liner to ensure a higher shear load and longer service life with the continued use of QD swivels. Specifications for Aero Precision M4E1-T PRO Series MOD4 5.56mm 13.9 inch CHF Barrel Complete Upper Receiver: Manufacturer: Aero Precision Caliber: 5.56mm Barrel Length: 13.9 in Barrel Profile: Hanson Gas System Length: Mid Length Barrel Twist Rate: 1-7 Muzzle Device: A2 Flash Hider Finish: Anodized Gun Model: M4 Fabric/Material: 8620 Steel Handguard Length: 12.7 in Gun Rail: Picatinny Gun Type: Rifle Gun Make: AR Platform Barrel Material: Cold Hammer Forged Bolt Carrier Group Included: No Charging Handle Included: No Features of Aero Precision M4E1-T PRO CHF M4 5.56mm 13.9 inch Complete Upper Receiver M4E1 Threaded Upper Receiver MOD 4 12.7 Inch Handguard 13.9 inch 5.56 Hanson Barrel Low Profile Gas Block and Gas Tube Product comes assembled Package Contents: Aero Precision M4E1-T PRO CHF M4 5.56mm 13.9 inch Complete Upper Receiver What firearm models does the manufacturer say Aero Precision M4E1-T PRO Series MOD4 5.56mm 13.9 inch CHF Barrel Complete Upper Receiver is compatible with? The manufacturer says that Aero Precision M4E1-T PRO Series MOD4 5.56mm 13.9 inch CHF Barrel Complete Upper Receiver is compatible with M4Aero Precision APAR700003D114: M4E1-T PRO CHF M4 5.56mm 13.9 inch Complete Upper Receiver Hanson Mid Length 1-7 Twist A2 Birdcage Anodized Black