Photo/Contact Tachometer NTCH-300 is a multifunctional device used to measure relative velocity, surface speed, frequency of motor. It combines photo tech. (RPM) & contact tech. (RPM, m/min, ft/min). It is applied to the measurement of frequency, cycle, pulse times and pulse distance. The time is based on quartz crystals and the maximum detecting distance 600 mm / 24 inch.