Marmot Bore Sight is a CAL 223 REM 5.56mm Red Laser Boresight . it is High Accuracy and Sturdy Brass Construction. Great for Gun Zeroing , Gun Sighting and Rifle Range Sighting Marmot Red Laser Bore Sight is Less Than 5nW. Caution: Visible Laser Radiation. Avoid Direct Eye Exposure Parameter: Laser Wave Length: 532-650nm Power: < 5nW Range for Sighting: 15-100yds Dot Size: 1¡±@50yds Tail Width:0.37in Head Width:0.25in Package Included: CAL 223 REM Bore Sight 3 Set of Batteries (9 total)