Meprolight's MPO-DS is a cost effective red dot sight designed for use on full sized pistols. It features a 3.5 MOA ret dot reticle, RMSc footprint, automatic and manual brightness controls, CR1632 battery lasting 2 years, and is water, shock, and fog proof. Features of the MPO-DS: RMSc Footprint3.5 MOA Red Dot ReticleCR1632 – 15,000+ hours battery lifeAutomatic and Manual Brightness ControlPower Saving Sleep ModeIPX7 Waterproof Meprolight USA Meprolight MPO-DS 3.5 MOA Open Pistol Sight w/RMSc Footprint 901243171