OPTI Speed takes your crossbow even further with a 20 to 100 yd BDC reticle, speed calibrated range from 215 to 450 fps, and an illuminated reticle for enhanced contrast against dark targets. Features: Glass etched reticle can be used with or without illumination Enhanced crossbow BDC reticle compensates for bolt drop and provides accurate hold over points from 20 to 100 yd Speed calibrated magnification system scales the reticle and target image to match bolt velocity (215 to 450 fps) Nitrogen gas filled Fully-coated lenses provide maximum brightness, clarity, and contrast Adjustable rheostat brightness control Durable leaf spring click adjustments for windage and elevation Wide field of view 1/2 MOA windage/elevation adjustments Weaver style 30 mm rings included TG988C 3 V CR2032 battery included