The Red Laser Bore Sight Kit includes the .223 red laser modular bore sight (MBS223) that allows you to choose between two battery options: the original 3 LR41/AG3 batteries for a compact bore sight, or the new external battery pack with long running (20+ hours!) 2 AAA batteries. Both systems are included with this kit along with four top arbors: AR243, AR3006, AR264 and AR762 to allow you to bore sight most major calibers. The AR243 arbor is used to bore sight all 308 based calibers- 243, 7mm-08, 260 Remington, 308/7.62x51, 338 Fed as well as 444 Marlin, 7mm STE, etc. The AR3006 arbor is used to bore sight 30-06, 25-06, 270, 280, 35 Whelen, 300 Savage, and some Mauser calibers. The AR264 arbor is used to bore sight many magnum calibers (7mm, 300 and 338 Win Mag, 240/300/340 Weatherby, etc). The AR762 arbor is used to bore sight 7.62x39, 220 Swift, 303 British, 35 Remington, and others.