The Extech 461950 is a tachometer for 1/8 DIN control cabinet installation. It measures the speed of motors, moving fans, pumps, gearboxes and propellers. Choice of 2 sensor transducer types: Proximity sensor - 3 mm (0.1 in.) target distance, range up to 36,000 rpm (600 Hz), Photoelectric sensor - 10 mm (0.4 in.) target distance, range up to 6,000 rpm (100 Hz). 1/8 DIN size. Power supply with 115/230 VAC 50/60 Hz.