Primary Arms SLx MD-21 Push Button 1x21mm Micro Reflex Red Dot Sight w/AutoLive & 2 MOA Red Dot Reticle Black. Weighing only 5 ounces the SLx MD-21 is both lightweight and rugged featuring upgraded mounting hardware for guaranteed rigidity and precision when you need it most. If you are looking for a taller mount check out the SLx 2.26in Mount for use with night vision or if you prefer a more headsup shooting position. The upgraded LED emitter offers complete night vision compatibility as well as a true Red Dot Bright reticle with an ultra-long runtime for full operability in any environment. Additionally the Autolive technology shuts off the reticle when no motion is detected for two minutes and immediately turns on as soon as you pick it up. This Primary Arms red dot sight is part of the SLx optics line. SLx optics have built a reputation for innovation reliability and value. All SLx optics undergo rigorous field-testing during development to best serve you in any environment. Specifications for Primary Arms SLx MD-21 Push Button 1x21mm Micro Reflex Red Dot Sight w/AutoLive: Manufacturer: Primary Arms Color: Black Magnification: 1 x Objective Lens Diameter: 21 mm Illumination Type: LED Illumination Color: Red Adjustment Click Value: 1/2 MOA Emitter Type: Enclosed Battery Type: Lithium Metal CR2032 Weight: 5 oz Red Dot Sights-Footprint: Not Applicable Features of Primary Arms SLx MD-21 Push Button 1x21mm Micro Reflex Red Dot Sight w/AutoLive Autolive technology extends battery life Fully multicoated lens Top mounted push button controls Night vision compatibility Shockproof and waterproof aluminum construction Standard microdot footprint Package Contents: Primary Arms SLx MD-21 Push Button 1x21mm Micro Reflex Red Dot Sight w/AutoLive Low mount and Absolute Cowitness mount with spacer (1.41in or 1.535in Height) Primary Arms 810027: SLx MD-21 Push Button 1x21mm Micro Reflex Red Dot Sight w/AutoLive & 2 MOA Red Dot Reticle Black