The Spacer Kit gives you five different brass spacers, all legibly numbered so you can adjust the spacing of the power tube O-ring. If your gun has bolt stick, use a longer one; if it leaks down the barrel, use a shorter one. Find one that works and stick with it! Quality machined brass to AGD standards. Comes with extra power tube O-ring, not shown. For Automag, Classic, Minimag, Sydarm, Micromag and Retro Valves with level 7 bolts.   NOT FOR LEVEL 10. Level 10 requires carriers and are sold with them.