The Primary Arms SLx MD-21S is an advanced micro dot sight that incorporates the latest technologies and materials to deliver exceptional performance. Weighing only 5 ounces, the SLx MD-21 is both lightweight and rugged, featuring the newest Primary Arms mounting hardware for guaranteed rigidity and precision when you need it most. The upgraded LED emitter offers complete night vision compatibility as well as a true Daylight Bright reticle with an ultra-long runtime for full operability in any environment.FeaturesAutolive Technology to Help Save Battery LifePush-Button Controls12 Illumination SettingsThe CQB Version Reticle has 4 Selectable Reticles