ElectroMagnetic Detector
MP Series - Ono Sokki
MP-900/9000 are chiefly used in conjunction with a detector gear mounted onto a rotating shaft by bringing the detector into proximity to the gear so that the detector outputs frequency signal of which is proportional to the rotational speed. So various types are available including low-priced, general purpose, oil proof and heat resistant types that you can make a choice for your usage.
Signal cables (except attached-cable types), extension cables and connectors are sold separately.