The HS403C is a solar red dot designed for day and night use, unaffected by extreme weather conditions. The efficient light emitting diodes and solar panels allow the green LED optic to run without a battery in many lighting conditions, additionally, the back-up battery (CR2032, included) lasts up to 5-years. There are 12 settings for the brightness of the reticle to match ambient lighting conditions. The side mounted buttons allow for easy operation without obstructing the user's vision. A low mount and 1/3 Co-witness mount included.