Easy-to-use, self-contained boresighting  system fits in the chamber of your rifle or  pistol and projects a powerful red laser  beam aligned with the bore axis for sighting  to the point-of-aim without firing a shot.  Works with scopes, holographic red dot  sights, and variety sights. Durable,  machined brass housing looks like a  cartridge case but actually contains the  entire laser system and batteries. Insert  the batteries and screw the cap on the  housing to turn on the laser; remove the  batteries to turn off. Insert the entire  assembly into the chamber, gently close the  action, and aim at a target 20-30 yards  away. Adjust windage and elevation of the  scope or sights so point-of-aim is zeroed  on.