Holosun HS503RThe HS503R is a 20mm micro sight designed for rifle and carbine applications. HS503R features a Rotary switch to select reticle intensity, Holosuns Red Super LED with 50k hour battery life, and MRS (Multi Reticle System) with 10 daylight and 2 night vision compatible reticle intensity settings. The HS503R 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