Holosun HS403B HS403B  Black Anodized 1 x 20mm 2 MOA Red Dot Reticle, HS403B is a 20mm micro sight designed for rifle and carbine applications. HS403B features Holosuns Red Super LED with 50k hour battery life, 10 daylight and 2 night vision compatible reticle intensity settings. Its housing is made from 6061 aluminum and includes both a lower 1/3 co-witness mount (1.63) and a low mount (.75) for low-comb height rifle applications.Additional features include Shake Awake technology, digital buttons for setting changes, rubber lens covers, and a side-mounted battery tray for the 2032 battery. HS403B is a versatile sight for users of all levels.