The Sig Sauer® ROMEO-M17 2 MOA Red Dot / 32 MOA Red Circle Dot Sight - Flat Dark Earth is engineered to provide a superior sight picture with unmatched accuracy and was designed specifically for the Sig Sauer M17 and M18 pistols. Boasting a durable 7075 aluminum housing, this red dot sight features an extremely low deck height that allows for a full sight picture and co-witness with standard-height iron sights. Further, this optic mounts from underneath the pistol slide and features a proprietary SIG-LOC™ (SIG Leverage Optimizing Connection) mounting interface that provides a secure and wobble-free optic and pistol lockup. The high-efficiency point source LED emitter offers 2 MOA dot/32 MOA circle reticles that are independently selectable (circle only, dot only, or circle/dot combination) for intuitive target acquisition while machined anti-reflection grooves on all rear surfaces provide reduced glare for a clear, crisp sight picture. Further, this red dot sight features 15 (12 daytime, 3 night vision compatible) user-controlled brightness settings so you can find the perfect sight picture for your environment and it is fully enclosed, sealed and gas purged for superior protection from the elements. Windage and elevation adjustments allow users to dial in this red dot sight for superior precision and accuracy while 2 drainage holes machined in the sides of the housing allow pooled liquid to escape for added durability. MOTAC™ (Motion Activated Illumination System) technology automatically powers up the unit when it senses motion and powers down when the weapon is idle for battery conservation. Operates on 1 CR2032 battery with up to 20,000 hours of battery life on the lowest setting and this red dot sight features a side-mounted battery compartment for easy battery changes. Backed by the Sig Sauer Infinite Guarantee lifetime warranty. Compatible with Sig Sauer M17/18 pistols ONLY.