For rifles, utilize the .223 boresight cartridge, where the laser is housed, for all .233 caliber weapons. For larger calibers, slide the cartridge into the appropriate arbor (i.e 30-06,308, 12 gauge) and insert into the chamber. A durable nylon case is included with boresight cartridge and it is specigically designed to hole the unit and serveral arboers for easy portability.