Check the listing for details. Mini Holographic Reflex Sight 3MOA Red Dot Sight Compact with 20mm Rail Mount. Color: Black, Condition: New. Listed at 19.89 USD. Product Description CAUTION: Looking direct at the sun through this sight may cause permanent eye damage. ==This tubeless-design reflex lens aperture provides a wide field of view. Suitable for rapid-firing or shooting of moving targets besides normal shooting. ==This red dot contains a separate switch with 3 steps for OFF, LOW BRIGHTNESS, HIGH BRIGHTNESS. When the switch turned to"off", power if off. When turning to "L" or "H", power is on and brightness of the dot changes from "LOW" to "HIGH". Parts: Switch for "off, low brightness, high brightness" Lens Weaver base knob Hex screws Elevation adjustment screw Windage adjustment screw Locking Screws Specifications: Dimensions: 40 mm (length) x 28 mm (width) x 35 mm (height) Weight: 2.1 OZ Dot Size: 3 MOA Color: Black Range: 30-100m Power: 1 x CR2032 battery Installing battery: Using the Allen(provide in package) wrench to remove two hex screws. Turn the sight upside down to remove the bottom part of sight(weave base). Replace it with 3V lithium battery(CR2032). Mounting: The red dot sight fits standard weaver base. Simply unscrew the weaver base knob and place the sight over weaver base on top of your device and tight it firmly. Windage and elevation adjustment: Before you make any adjustment, make sure using the flat screw driver(provide in package) loosing two locking screws to void damage or merchandise. Using the flat screw driver to adjust elevation adjustment screw and windage adjustment screw. Tighten two locking screws after adjustment finished. Package: Storage Box Cleaning Cloth Owner's Manual Two Hex Wrenches Tactical Holographic Red Dot Sight