Starrett, 52158, Mechanical Micrometer Heads; Minimum Measurement (Decimal Inch): 0.0000; Maximum Measurement (Decimal Inch): 1.0000; Thimble Dia (Decimal Inch): 0.5000; Digital Counter: No; Spindle Length (Decimal Inch): 1.0000; Spindle Type: Flat; Rotating Spindle: Yes; Calibrated: No