Standard Picatinny rail with two bolt holes. Standard Picatinny rail , which can be used as fastening devices on airsoft guns as well as almost any other subject . Of course, if you can attach the bar to this very subject. ) Has two versions: with Hole bolt without them.Print , attach to , on what it will be used ( can be done either by using 2 bolts , if this is not possible , then glue the glue) . After check whether strap securely glued . Then you can use it.