The HE403R-GD is a small compact micro Gold dot optic that features Holosuns new Rheo Stat Dial to adjust brightness settings. Employing our LED technology, The HE403R-GD can achieve constant on battery life of up to 100,000 hours on medium setting. Specifications for Holosun HE403R Micro Red Dot Sight: Color: Black Finish: MAO Fabric/Material: 6061-T6 Aluminum Magnification: 1 x Objective Lens Diameter: 20 mm Objective Window Size: 20 mm Reticle: 2 MOA Dot Illumination Type: LED Illumination Color: Amber Brightness Settings: 10 Eye Relief: Unlimited Adjustment Type: MOA Adjustment Click Value: 0.5 MOA W/E Travel at 100 Yds: 50 MOA Parallax: Parallax Free Optical Coating: Coated Attachment/Mount Type: Picatinny Battery Type: CR2032 Battery Life: 50000 hours Operating Temperature: -22 - 140 Fahrenheit Water Resistance Level: IP67 Shockproof: Yes Fogproof: Yes Length: 2.75 in Width: 1.43 in Height: 1.62 in Weight: 3.53 oz Battery Quantity: 1