The Firefield .308 Win Laser Bore Sight is a useful accessory for quickly and precisely zeroing your firearm. With this tool, will you not waste time and ammo by tediously aligning your optic with a trial-and-error zeroing technique. To zero your weapon with Firefield's Laser Bore Sight, simply place the cartridge-sized laser in the chamber, turn on the laser and align the sight with the red dot projected on the target. You will achieve a perfect zero in moments without using your rounds or precious time at the range. The laser has durable anodized aluminum housing and is designed to seamlessly fit in the chamber of your .308 Winchester caliber rifle.