Hawke Optics Endurance 1x21mm 3 MOA Dot / Circle Dot Green Reflex Sight - High performance, slimline reflex red dot sights built for accuracy and durability. Multiple reticles at the press of a button: Endurance features a user-selectable 3 MOA dot, 30 MOA Circle, and Circle + Dot multi-reticle system with green illumination. A 10-stage digital brightness control includes 2 night-vision compatible settings for enhanced flexibility. Endurance reflex sights utilize the RMSc footprint for seamless direct mounting to slimline pistols, and include a removable Weaver/Picatinny base for an ultra-compact solution on rimfire, air rifles, AR's, and shotguns. A.I.M. (Auto Illumination Mode) conserves battery power by putting the sight into standby mode when no movement is detected for 5 minutes. The sight automatically powers-on immediately when it senses movement. Paired with a high efficiency LED emitter, Endurance Reflex sights can run at a daylight-bright setting for several years on a single battery.