Our 10 pack of one time use crush washers is perfect for your precision bolt action rifle or AR15 rifle or any other sporter rifle. It allows you to perfectly time your muzzle brake or compensator or suppressor. Keeps the install process overall simple and is a one time use crush washer. Precision machined from spring steel and finished off in black oxide for a sleek black look. Please ensure your barrel is threaded 1/2-28 thread pitch.