PRI Flip Up Front Sight with .750 w/ set screws.  The base is solid 4140 cast steel with provision for the gas tube an integral part of the unit. Front post is constructed of T6 6061 hard coated black anodized aluminum. Front post uses the standard A2 post for height adjustment. Sight weighs 4.8 ounces. The center line of barrel to line of sight is 2.57"  This sight requires the barrel to have flats machined into the barrel.