The Holosun HE507K X2 MRS Green 2 MOA Dot / 32 MOA Circle Open Reflex Sight is a parallax-free green dot sight featuring a proprietary Multiple Reticle System with a user-selectable 2 MOA dot or 32 MOA circle reticle for intuitive target acquisition. The durable 7075-T6 aluminum housing offers lasting strength and durability for exceptional performance in challenging environments, and multilayer reflective glass lenses deflect stray light away from your eye. The HS507K X2 boasts 12 brightness settings (10 daylight; 2 night vision) for exceptional clarity in any lighting, while Shake Awake technology automatically activates the red dot when it detects motion for an instant, hands-free activation, and automatically powers down the unit when the weapon is idle. Plus, the HS507K X2 operates on a single CR1632 battery (included) for an impressive battery life of up to 50,000 hours of battery life. IP67 waterproof.