The HHA Tetra XB Crossbow Scope Mount allows you to use a single crosshair, variable magnification scope and adjust the angle of the scope to the distance of your animal. By spinning the dial, the mount raises or lowers to the appropriate level for accurate shooting. That way you only have to deal with one crosshair, and it will adjust out to 100 yards with pinpoint precision. The HHA Optimizer scope mount bolts to most crossbow scope rails (occasionally some filing of the mount lock will allow for tightening on narrow rails) and can be used with scopes as well as red dots.
The Hawke Vantage scope gives you a 2-7 illuminated single crosshair scope kit that as adjustable parallax so you can tune the scope to work in crossbow ranges.
The Hawke 1X Prism red dot is perfect for those looking for a 1X scope rule legal optic that you can adjust for different distances. just turn the dial to the range of your target, put the red dot where you want to hit and squeeze the trigger.