Internal diameters are quickly measured and the measurement read at a glance from the high contrast six digit LCD display. Resolution 0.001mm/0.00005" (on display unit). Preset, Zero set, ABS and Hold features. Auto Power-off - power-on by rotating thimble. SPC compatible. Accuracy:Instrument Error: 7-20mm 2mm. 20-100mm 3mm. 100-200mm 5mm