Tru-Glo 24x33mm Multi-Dot Red Dot Crossbow Sight, Black 1960Fast and accuarate trajectory compensating system. Simply click the selector knob to the velocity you are shooting and use the pre calibrated aiming points to hit targets at aproximately 20, 30, 40, 50 yards. 2 choices of reticle color for contrast against any target background lighting 24x33mm objective lens diameter Wide field of view Shock resistant Unlimited eye relief 10 position rheostat for brightness control, 5 settings for each color