I broke my previous bore sight, so I grabbed this one since it was very reasonably priced. All you have to do is turn the battery chamber. This bore sighting laser is a huge money saver! I sighted in my 22 magnum rifle, and it was spot-on at 50 yards. you will notice if you spin the boresight, and you don't have it seated properly, the laser will actually move. Just make sure the laser is nice and solidly in place, and you won't have any problems at all. A very happy Hunter here.