Meprolights MPO-DF is a cost effective red dot sight designed for use on full sized pistols. It features a 3.5 MOA ret dot reticle, RMR footprint, automatic and manual brightness controls, CR1632 battery lasting 2 years, and is water, shock, and fog proof.Features : RMR Footprint 3.5 MOA Red Dot Reticle CR1632 15,000+ hours battery life Automatic and Manual Brightness Control Power Saving Sleep Mode IPX7 Waterproof