Holosun Shake Awake Micro Red Dot 1x20mm Holo Sight - Red Dot - The 403B is a small compact micro red dot optic. Employing Holosun's LED technology, the lifetime for one CR2032 battery can be up to 5 years. This optic features our "Shake Awake" technology that powers the optic on with slight movement of the 403B. It may be installed on various firearms such as shotguns, pistols ,air rifles and crossbows. The HS403B is compatible with standard mounts. Designed for day and night use; New advanced technology LED allows up to 50,000 hours of operation on one CR2032 battery; 2 MOA on dot size; Reduced training time and ammunition; Unlimited field of view; Parallax-free with unlimited eye relief; Unaffected by extreme weather conditions; Durable and reliable construction; Low mount and 1/3 Co-witness mount included;