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 28,000-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.