The 461950 is a 1/8 DIN panel tachometer. Rotational motor speed, moving fans, pumps, gears, and propellers should all be measured. There are two sensor pickup kinds available: proximity sensor and 0.1 in. (3 mm) target distance, range up to 36,000rpm (600Hz), photoelectric sensor 0.4 in. (10 mm) target distance, range of up to 6,000 rpm (100Hz). 1/8 DIN size. 115/230V AC, 50/60Hz.