AIM Sports Inc Complete Rifle Build Kit AR-15 5.56x45mm NATO 16-inch Barrel Mid-Length Gas Tube Low Profile Gas Block Black Hardcoat Anodized Aluminum. Specifications for AIM Sports Inc Complete AR-15 5.56x45mm NATO 16in Upper Receiver W/ BCG LPK & Mil Spec Stock Buffer Kit: Manufacturer: AIM Sports Inc Caliber: 5.56x45mm NATO Overall Length: 24.5 in Barrel Length: 16 in Barrel Profile: Government Gas System Length: Mid Length Barrel Twist Rate: 1-8 Firearms Threads Per Inch: 1/2x24 Muzzle Device: A2 Flash Hider Finish: Hard Coat Anodize Color: Black Gun Model: AR-15 Fabric/Material: 4150 Chrome Moly Vanadium Handguard Length: 15 in Gun Type: Rifle Gun Make: AR Platform Features of AIM Sports Inc Complete AR-15 5.56x45mm NATO 16in Upper Receiver W/ BCG LPK & Mil Spec Stock Buffer Kit A2 muzzle brake and crush washer Complete Upper with dust cover and forward assist Mil Spec Buffer Kit - 3.0oz buffer carbine spring castle nut end plate mil-spec buffer and stock Lower Parts Kit - Complete lower parts kit includes fire control group and A2 Grip Package Contents: AIM Sports Inc Complete AR-15 5.56x45mm NATO 16in Upper Receiver W/ BCG LPK & Mil Spec Stock Buffer Kit What firearm models does the manufacturer say AIM Sports Inc Complete AR-15 5.56x45mm NATO 16in Upper Receiver W/ BCG LPK & Mil Spec Stock Buffer Kit is compatible with? The manufacturer suggests that AIM Sports Inc Complete AR-15 5.56x45mm NATO 16in Upper Receiver W/ BCG LPK & Mil Spec Stock Buffer Kit is compatible with AR-15AIM Sports Inc AR5CUB5: Complete Rifle Build Kit AR-15 5.56x45mm NATO 16-inch Barrel Mid-Length Gas Tube Low Profile Gas Block Black Hardcoat Anodized Aluminum Black Large