Sightmark .40 S&W Premium Laser BoresightTested and recommended by the National Tactical Officers Association the Sightmark Boresight significantly reduces wasted cartridges and shells. Chamber the device like a regular cartridge and a red laser dot shows exactly where you're aiming. Simply adjust your sights or scope and save your extra ammo for the hunt. Includes a carrying case three (3) AG3 batteries and instructions.