The SCS-PDP-GR (Solar Charging Sight) is designed for Walther PDP 2.0 optics ready handguns. It is designed to attach directly to the slide without an adapter plate and uses our solar charging system with multidirectional light sensors to automatically adjust brightness. The SCS can potentially operate indefinitely using an internal, rechargeable 20,000-hour battery meaning you will never need to change batteries again. Included is an intensity override function which locks the optic into a high brightness mode for 30 minutes. 20,000-Hour Power Reserve Solar Charging Internal Battery Multi-Sensor Auto Brightness Brightness Intensity Override System Multiple Mfg: Holosun