The Mepro MPO-DS is an open reflex red dot sight designed for subcompact or slimline pistols. This cost-effective optic punches far above its cost. It features a 3.5 MOA red dot reticle, RMSc/JPointA(R) footprint, automatic brightness control, CR2032 battery lasting 3 years plus while being water, shock, and fog proof. The Mepro MPO-DS allows you to upgrade your current sighting system with money left over for more ammo. The MeprolightA(R) name means we only produce products we, ourselves use and carry in defense of ourselves and our families. Choose the best, choose MeprolightA(R). SPECS Footprint: RMSc/JPointA(R) Objective Lens Diameter: W: 0.82"x H: 0. Mfg: Meprolight