The Lindcraft 3/8" x sixteen threads and 1/4" x twenty threads Barrell adapter is CNC machined with gear quality flutes which allow hand tightening. It is primarily used as a thread converter, either male or female, and 1/4-20 to 3/8-16, for use with Noga Israeli Arms, but they can be used when ever you need to convert the size and sex of either a 1/4-20 or 3/8-16 screw or bolt. Made of 6061 T6 black anodized aluminum.