Garrett GTI 2500 Owner's Manual page 59

Size/Depth on the Imaging Grid
As you are locating your target precisely
by moving the searchcoil while press-
ing and holding the TREASURE IMAGING
touchpad, you will observe size and depth
changing on TreasureVision's Imaging
Grid. The coil must be centered directly
over the target to produce accurate size
and depth information. As you approach
the target, therefore, its indicated depth
on the Imaging Grid will become shallower
and its size smaller.
Thus, the correct reading on the Imaging
Grid will always be the shallowest and
smallest. This is achieved only when the
searchcoil is positioned directly over the
target.
Graphic Target Imaging 2500 - 59