These are precision stainless steel calipers that display measurements in inches with fractions or millimeters. They are constructed of high quality hardened and ground stainless steel components and included the same advanced Wixey Technology features found in all our other Digital Readout products. The large easy to read display reads in inches with fractions or millimeters. The fractions are displayed using "Precise Fraction Technology" which gives you 4 times the accuracy of other fraction readouts. The decimal inches are displayed in .001-inch increments, the fractions in 1/64-inch, and the millimeters in .05mm increments. Accuracy is .001 decimal inches, 1/500 fraction inches, and .025mm metric. These calipers incorporate precision measuring features found in top of the line measuring tools used in metal working. The precision ground measuring faces allow for outside, inside, depth and step measurements.