The aiming dot illumination changes automatically according to the surrounding available light to maintain good contrast between the aiming dot and the target area. The fiber optic collector located on the front face gathers maximum light when shooting from within a dark enclosed space toward a bright target area. RS-22 can be equipped with a photo-chromatic lens which, will darken to improve contrast when aiming against extremely bright backgrounds. The sight is designed with back-Up Sight, automatically zeroed at the same time as the optical sight, and having a line of sight parallel to the optical line of sight. Using the emergency sight, the soldier can hit a full size figure at 100 meters – 7 shots out of 10.