Model 512. XBOW was designed with the crossbow hunter in mind. The XBOW utilizes the unique properties of holography to create optimal range scaling data in a heads-up display. A pre-calculated ranging scale is projected on the target and measures the back to the belly of a standard whitetail deer (18''). Simply position the base of the scale on the belly and read the yardage line that crosses the back. This integral ranging pattern eliminates unnecessary body movement or added noise while in the stand since the ranging and aiming information are both displayed in the same sight picture.