This Anderson Manufacturing complete upper receiver has the following specs:

COUNTRY OF MANUFACTURE: United States
UPPER RECEIVER MATERIAL: Forged 7075 T6 Aluminum
RECEIVER FINISH: Type 3 Hard Anodized, Black
BOLT CARRIER FINISH: Nitride
BOLT CARRIER MATERIAL: 8620 Steel
BOLT FINISH: Nitride
BOLT MATERIAL: 9310 Steel
BARREL MATERIAL: 4150 Chrome Moly Vanadium
BARREL LENGTH: 7.5 Inch
BARREL FINISH: Nitride
BARREL CONTOUR: Government Profile
TWIST RATE: 1:7
GAS SYSTEM LENGTH: Pistol Length
GAS SYSTEM TYPE: Low Profile
GAS BLOCK DIAMETER: .750 inch
CHARGING HANDLE: Standard Charging Handle
BOLT CARRIER GROUP: Standard M16 Profile
HANDGUARD: M-Lok
HAND GUARD LENGTH: 7.28 inch
THREAD PATTERN: 1/2 – 28
MUZZLE DEVICE: Knight Stalker Flash Hider

COMPATIBILITY: Standard Multi-cal Lower Receivers