【Safe & Adjustable Laser Beam】Bright and precision red laser sight, Safe beam intensity/wavelength: <5mW peak, 532nm, Class IIIA. Highly visible laser in any environments which can reach up to 50-100 ft during the day and up to 600-1000 ft at night.-- Laser Wavelength: 632 to 650 nm -- Battery Type: AG3/LR41 -- Range for Sighting: 15 to 100 yds -- Dot Size: 2 in @100yd -- Operation: on/off end cap -- Operating Temp: F/C 14 to 122 / -10 to 50 F/C CAUTION -- Be sure that your firearm is unloaded and pointed in a safe direction before attempting to insert the boresighter. -- Do not dry-fire your firearm while the boresighter is inserted. It may cause damage to the bore sight. BATTERY INSTALLATION 1.Twist the end cap of the boresighter counter clockwise to open the battery housing. And insert the 3 AG3/LR41 batteries into the battery negative end first. 2.Be certain that the batteries are all facing in the proper direction to ensure proper function of your boresighter. 3.As the bore sight doesn’t have the on/off switch, please remove the batteries after using. HOW TO ZERO YOUR FIREARM? 1.Set your firearm in a gun vise or other stable platform so that it does not move. 2.Insert your boresighter fully into the empty chamber. And sight in your firearm at any desired distance that the laser is visible (25 yards is recommended). 3.Align your firearm so that the laser is centered on the bull’s eyes. 4.Adjust your scope (according to the manufacturers specifications) so that the reticle of the scope matches with the laser and bull’s-dyd alignment. 5.Remember to remove the batteries of your bore sight to preserve the battery life, and store in a cool, dry place.