The Viridian 981-0176 is a RFX42 Micro Closed Emitter Green Dot Sight for pistols featuring a 3.5 MOA green dot a fully enclosed aluminum body and the Shield RMSc footprint for easy mounting on a variety of pistols. It boasts Instant On Activity a side-loading battery tray for a 28000-hour battery life 10 brightness settings and durable shockproof and waterproof construction. Optics: The RFX42 features a 3.5 MOA (minute of angle) green dot reticle. It has a 1x magnification and a 21mm objective lens. Design: It is a compact sight with a durable aluminum construction. Compatibility: The sight is designed to fit the Shield footprint a standard for mounting optics on certain pistol slides. Power: CR2032 lithium battery. Dimensions: It has a length of 1.60 inches a width of 1.00 inch and a height of 1.04 inches.