SCS Glock MOS Green Dot Sight - HolosunThe SCS can potentially operate indefinitely using an internal, rechargeable 20,000 hour battery meaning under even moderate exposure to bright light, you will never need to change batteries again. The SCS also includes an intensity override function which locks the optic into a high brightness mode for 30 minutes and a low power indicator which warns of low battery days before charging is needed. In the Box Mounting Screws User Manual Lens Cloth