Range: 1.0 in. . Graduations: .001 in.. Continuous forward and reverse reading with revolution counter. Reading: 0-100. Diameter: 2-1/4 in.. Rack and pinion construction. Lug back. 3/8 "diameter shank This is a face type A dial indicator that is also included in several of our popular test kits. This particular one is separate, it's rack and pinion construction is very durable for a long life.