Mitutoyo Digimatic Holtest - 3 Point Internal Micrometer Specifications include... 8.00" - 9.00" / 203.20 - 228.60mm Measuring Range 0.00005" / 0.001mm Resolution + .0002" Accuracy Features include... TiN-coated contact points provide excellent durability, impact resistance, and allow the instrument to measure right to the bottom of a blind hole. Large LCD readout. With Ratchet Stop for constant force. Measurement can be taken closer to the bottom of the blind bore. Can measure deep holes by attaching an Extension rod (optional). Setting rings for origin point setting are optional. Supplied in fitted plastic case. Functions include... Zero-setting, Data hold, Data output, Preset, inch/mm conversion (inch/mm models) Alarm: Low voltage, Counting value composition error