Deltronic Standard Thread Measuring 3-Wire SetsEach set of 3 wires is contained in a screw top vial. The vial is packaged in a hinged lid box which is labeled to show pitch and Calibrated Wire Size. The Calibrated Wire Size is also shown on the Certification of Accuracy contained in each set box. Features include Commonality, three wires within each set are within 5 millionths (. 000,005), . 00031mm of calibrated size. Set Diameter is within 20 millionths (. 000,020), . 0005mm of best wire size