Rotating Spindle Type. The thin measuring discs, with .030" edge thickness, enter narrow grooves, slots, and recesses, to take measurements on work sections such as ribs, lands, fins, cutting edges on form tools, and chordal thickness on gear teeth. Measuring discs are hardened, ground, and micro-lapped for greater accuracy. Extra-large disc, .787" in diameter, with .030" edge thickness to enter narrow recesses. With heat-insulating grip cover on the frame. Appropriate standards supplied. Supplied with a fitted carrying case.