The Holosun HE403C-GR is a 20mm Micro Reflex Sight created with Solar Failsafe™ which means you won't have to worry about battery failure. With the added feature of automatic brightness adjustment, you'll be able to use your red-dot in almost any lighting condition. Topping it off is T6 Aluminum housing and a 2MOA green dot reticle, making this a must-have optic for any rifle or PDW.