The 3900 Series Electronic Indicator has simple, powerful, easy-to-use functions, all at an attractive price. The 3900M-5 metric version has a 12.5mm range, 0.01mm Resolution and a 8 mm stem diameter and a M2.5 X .45 spindle thread. Ships with lug-on-center back installed, and includes a flat back as an accessory, along with a plastic storage case.