Calibrated for crossbows that shoot in the 330 FPS range, this 20, 30, 40, and 50-yard combo illuminated dot and crosshair configuration is housed in a lightweight 8.5-inch aluminum tube equipped with fully-coated 3x optics. The illuminated dots are positioned at the intersection of each of the duplex crosshairs. The fourth dot is free-standing and situated directly below the 40-yard crosshair. In the field, you select non-illuminated black dots or one of two illuminated, colored dots (red or green) controlled by a five-position rheostat so you can match the illumination intensity to your hunting conditions.