A simple solution for sighting in your high performance firearm, the AIM Sports Red Laser Boresight makes accurate sighting fast and easy. Enclosed in a perfectly-sized brass case, these boresights simply slide into the chamber of your firearm and project a steady laser you can reference to lock in your sights. Sized to fit a specific caliber or range of calibers, each of these boresights projects a powerful, easy-to-see 5mW red laser to your target. Runs on a LR41-type battery. Brass construction will not harm chamber. Easy-to-use solution for sighting in firearm Slides into the chamber of your firearm Projects a powerful, easy-to-see 5mW red laser Runs on a LR41-type battery Soft brass construction