TacFire's Clamp On Low Profile Gas Block is CNC machined from steel with a erosion resistant parkerized finish. It replaces the an existing A2 front sight and is compatible with 5.56/223 rifle with .705" barrel diameter. A roll pin, screw set and hex wrench. This model has a black finish.Our Low profile Clamp On micro gas block is CNC precision machined with superior quality steel. It is Heat treated, Erosion resistant with a Parkerized Finish. This Low Pro 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 compatible with 5.56/.223 with a 0.750 diameter barrel. Roll pin and set screws are included. No modification to your barrel is required. Features: Roll pin included Hex wrench included