Aero Precision M4E1-T PRO 5.56x45 16 in Upper Receiver Hanson Mid Length 1-7 Twist A2 Birdcage OD Green 11D112-1. 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 5.56x45 16 in Upper Receiver: Manufacturer: Aero Precision Caliber: 5.56x45mm NATO Barrel Length: 16 in Barrel Profile: Hanson Gas System Length: Mid Length Barrel Twist Rate: 1-7 Muzzle Device: A2 Flash Hider Finish: Anodized Handguard Length: 15 in Barrel Material: Cold Hammer Forged Features of Aero Precision M4E1-T PRO 5.56x45 16 in Upper Receiver Ambidextrous Controls: Ergonomically designed 7075 Aluminum levers allow the user to easily charge their firearm with either hand while remaining low profile and comfortable when slung. Robust Construction: Reduced chamfer angles on the 7075 Aluminum reinforced bar design provide a strong foundation for the BREACH that is resistant to rotational flex or breakage. Patent-pending Lever Mechanism: Transfers force-of-use away from the roll pins and into the top/head portion of the reinforced bar protecting the charging handle in the most demanding circumstances. Gas Deflection Shelf: Aligns with the upper receiver to redirect gas flow away from the users face when shooting suppressed. Functional Design: It is not all just good looks. Stylistic cuts on the charging handle also help to clear stuck on carbon and debris from the upper receiver while the spacer design seals and protects the lever mechanism from debris. Full top picatinny rail for optional attachments Quick disconnect sling socket at the 3 6 and 9 o'clock positions Compatible with low profile gas blocks 1.2" Inside diameter 1.5" Outside diameter Compatible with mil-spec AR15 upper receivers and barrels 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 Package Contents: Aero Precision M4E1-T PRO 5.56x45 16 in Upper Receiver Aero Precision 11D112-1: M4E1-T PRO 5.56x45 16 in Upper Receiver Hanson Mid Length 1-7 Twist A2 Birdcage OD Green