The 461950-NIST is a 1/8 DIN Panel Tachometer. Measure rotational motor speed, moving fans, pumps, gears, propeller devices. Choice of 2 sensor pickup types: Proximity sensor-0.1 in. (3 mm) target distance, range up to 36,000rpm (600Hz); Photoelectric sensor-0.4 in. (10 mm) target distance, range up to 6,000rpm (100Hz). 1/8 DIN size. Powered by 115/230VAC 50/60Hz. Includes certificate traceable to NIST.