The Troy Industries low profile gas block replaces the standard AR-15 front sight. The slim design allows users to install rail systems and free float tubes that extend past the front sight/ gas block assembly location. The gas block is stainless steel with a black oxide finish. It is secured with two set screws located on the bottom of the block. Notes Will not cover front taper pin hole on a barrel that has a standard mil-spec sight installed. Will fit under rail systems and free float tubes. Gas tube roll pin is not included.