... range 1.2~220mm 2.auto null point calibration,sound velocity measuring 3.data storage/inquiry/deletion ... meter, noise meter, vibration meter, ultrasonic thickness gauge, film/coating thickness gauge, digital hygrothermograph, high voltage megohmmeter, ground resistance ... measuring lower limitΦ20*3mm(steel)auto null point calibration, system error correctionlinear auto compensation, correct nonlinear ...