AIM Sports Inc Complete AR Pistol Upper Receiver w/ BCG 5.56 NATO 10.5in Barrel M4 Profile Carbine 1-8 Twist 1/2x28 Thread 10M-LOK Free Float. 5" AR Pistol Upper Specifications for AIM Sports Inc Complete AR-15 5.56x45mm NATO 10.5in Pistol Upper Receiver w/BCG: Manufacturer: AIM Sports Inc Caliber: 5.56x45mm NATO Muzzle Device: A2 Flash Hider Finish: Type III Hardcoat Anodized Color: Black Gun Model: M4 Fabric/Material: 7075-T6 Aluminum Barrel Material: 4150 Chrome Moly Vanadium Condition: New Features of AIM Sports Inc Complete AR-15 5.56x45mm NATO 10.5in Pistol Upper Receiver w/BCG UPPER: Mil-Spec Forged 7075-T6 completely assembled upper receiver. Type III hard coat anodized for maximum durability. M4 Barrel Extensions BARREL: 10.5in 4150 Chrome Moly Vanadium Steel. 5.56 NATO Chamber . Nitride finished for protection against corrosion. BOLT CARRIER GROUP: Carrier body is 8620 steel and bolt is 9310 tool steel. Both are Nitride finished with excellent lubricity and corrosion resistance properties. Full Auto Profile RAIL: 13.5in AIM Wraith M-LOK Rail Package Contents: AIM Sports Inc Complete AR-15 5.56x45mm NATO 10.5in Pistol Upper Receiver w/BCG What firearm models does the manufacturer say AIM Sports Inc Complete AR-15 5.56x45mm NATO 10.5in Pistol Upper Receiver w/BCG is compatible with? The manufacturer suggests that AIM Sports Inc Complete AR-15 5.56x45mm NATO 10.5in Pistol Upper Receiver w/BCG is compatible with M4AIM Sports Inc AR5CUB8: Complete AR Pistol Upper Receiver w/ BCG 5.56 NATO 10.5in Barrel M4 Profile Carbine 1-8 Twist 1/2x28 Thread 10M-LOK Free Float Handguard A2 Birdcage Flash Hider Nitride Black