) ,which have longer service life,it give you longer aiming correct Tipfun 9mm Bore Sight Cal Red Dot Boresighter High accuracy,the fastest red dot laser zeroing and sighting system and save you time and cartridges. Sig Sauer MCX Rattler 300 Blackout (7.62x35mm) Pistol 5.5 Barrel 30+1 Suitable for the 9mm chamber. Use only 2 batteries at a time. 【Design】 Light and compact, and easy to sit perfectly in the bore. How to use the bore sight? 1., Unscrew the back cap from the bore sight by turning counter clockwise., 2., Insert batteries (+ side up) inside the rear opening , 3., Turn the screw cap clockwise to tighten the cap (the laser is now on)., 4., Place bore sight in your rifle’s chamber carefully and close the bolt., 5., To remove - open the bolt if it does not automatically extract, manually remove the unit by tilting the rifle’s barrel upward (always practicing safe firearm practices)., 6., Unscrew the back and remove the batteries to turn the bore sight off . Tipfun 9MM/ .243 .308/6.5MM/300BLK 7.62x35mm/.44mag/30-06/25-06/270 Cal Rem Gauge Bore Sight Red Dot Boresighter with Batteries. $8.99 Faster gun zeroing,high accuracy,reduce cartridges and shells wasted. Class IIIA laser, less than 5mW. High Quality Laser Module Using high quality module with qualified electronic and assembled by professional craftsmen,it provides with a long service life of trouble-free use. Bore Sight Laser Vector Optics .243 .308 Win. 7.62x51 Mm 7mm-08 Rem Cartridge Red Laser Bore Sigh Taurus G3c Accessories