Our Low proflie micro gas block is constructed of anodized aircraft grade aluminum with a Hard Coat Type 3 Finish. The Low profile Micro gas block replaces the existing A2 front sight, and is sleek and small to allow a longer rail to be placed over. Can be used when installing a Mid Length, Specter Length or Rifle Length hand guard to a shorter length gas system barrel. It is compatibe with .308 & 5.56/.223 Bull Barrel with a .936 diameter barrel. Roll pin & set screws are included. No modification to your barrel is required.