AimSHOT BS204 Ruger 204 laser bore sight module is designed to make it quick and easy to bore sight your rifle chambered in 204 ruger. This is an actual laser bore sight, no additional parts are needed. Insert brass laser module into chamber and align scope reticle to match laser beam at 20 yards. Remove laser and proceed to the range for final adjustments at whatever range you want your zero. The Diode Module includes CR123 "button-type" battery cells and a foam lined storage c.