Fully enclosed, sealed, and purged optical system, for ultimate protection from the elements; Mounts from underneath the pistol slide, re-using the MHS pistol rear sight block and sight block screw; 7075 Aluminum housing; Integrated gas deflector on the front of the housing; Machined anti-reflection grooves on all rear surfaces for reduced glare; Extremely low deck height, allowing a full sight picture and co-witness with standard-height sights; SIG-LOC (SIG Leverage Optimizing Connection) proprietary mounting interface, for the ultimate optic/pistol lockup; High-efficiency point source LED emitter, with 2 MOA dot/32 MOA circle reticle. Reticles are independently selectable (circle only, dot only, or circle/dot combination); MOTAC (Motion Activated Illumination); MAGNETAC (Magnetic Activation); D.A.R.C. (Dark Adaptive Reticles and Coatings); Designed, developed, tested and fully assembled in the USA