An optic that requires not batteries, the ReadyDot Micro Reflex Optic from Ruger, is now available... "The Ruger® ReadyDot™ Optic is an easy-to-use micro reflex sight system designed to co-witness on Ruger's MAX-9® pistol. It fits a variety of EDC compact handguns with Shield RMSc footprints and can be co-witnessed to back up iron sights. The profile and shape were designed to provide visual guidance for fast target acquisition and EDC capability.