X-Caliber inserts can be installed and removed without tools or any modification to the shotgun. Inserts available for 12ga. shotguns include .380acp, 9mm Luger, .38spl/.357mag, 40S&W, .44mag, .45ACP, 410ga/.45Colt and 20ga. Inserts for 20ga shotguns include 9mm luger, .38spl/.357mag, .45ACP and 410ga/.45Colt. The complete kit comes in a high quality nylon case that holds all of the inserts safely and securely. Inserts can also be purchased individually.