Measures the depth of holes, slots, shoulders, and projections quickly and easily to .001" or 0.01mm. All heads are accurate to .0001" or 0.002mm. 440 gauges are furnished with a 2,1/2" (63.5mm) base and 1/8" (3.2mm) diameter measuring rods. All reading surfaces have a satin chrome finish that resists rust and provides a no-glare background for the sharp lines and figures. Ring-type lock nut for quick and sure locking. Furnished in an attractive protective case.