HORIZONTAL DISTANCE “HD” MODE
HD mode measures the horizontal distance to the target. The straight line distance is shown on the upper distance readout and the HD component is shown on the lower distance readout. This is especially useful for measuring the bullet compensated distance to a target.
If shooting at high angles in the mountains, firing airguns that have loopy trajectories, or shooting bows from a tree stand, HD mode gives a more realistic distance for use when calculating holdover aim points.