AMP Tactical Micro Reflex SightThis sight is light activated and comes with adjustment tool, screwdriver, and cleaning cloth and extra set of batteries. The sight has a hard plastic cover for when the sight is not in use. When you remove the sight, a photo cell on the front of the sight automatically detects ambient light and turns the sight on. Operation is still adequate in low-light as well, as the photo cell will automatically dim the sight in low light. Be sure to reinstall the cover for when the sight is not in use to reduce battery drain.