Abstract: A device for precisely measuring the depths of cuts of a Mercedes Benz key at the critical depth locations which determine the unique characteristics of each such key. In a first embodiment for measuring a single shelf key, the key is measured by a projecting probe of a circular gauge, by moving the key via a slide plate. The slide plate is incremented by a rack-and-pinion arrangement, the rack forming part of one side edge surface of the slide plate. A stop member cooperates with cut-outs formed in the other side edge surface of the slide plate for holding the slide plate, and therefore the key, at each of the critical locations where depth of cut is to be measured. In the second embodiment, a double shelf key may be measured by the use of a pair of oppositely disposed and aligned probe tips of a pair of circular measuring gauges.