The Timber Creek Outdoors Low Profile Gas Block is precision machined from steel with a black phosphate finish. It will fit under most free float handguards on the market. The dual set screws securely attaches to AR barrels with a .750" diameter gas seat. Upgrade your modern sporting rifle with this performance part. Machined Durable Steel Manganese Phosphate Finish .750" Diameter Aesthetic Cuts Black Fits AR Barrels with a .750" Diameter Gas Seat