By project a laser beam from the center of the barrel axis of fire arm, this laser bore sight collimator allows you to instantly & accurately set your sight or scope, etc.
The laser light emitted from the laser bore tool travels in a straight line while the bullet follows a trajectory. Even though theuse of this device will get you very close, the final adjustment should be made at the range.
Fasten (rotate) head to light on. Release (rotate) to light off.