4 Digital LED Tachometer RPM Speed Meter +Hall Proximity Switch Sensor NPN 8-24V Product Feature 100% brand new and high quality. 4-digits display, clear and easy for readings. Mini size, high performance and fast reaction speed. With good stability, high accuracy, anti-interference ability. Using the latest A/D conversion chip, high stability reference IC and stick chip components. It can be applied to voltage and current measurement, also can be an external sensor to measure temperature, pressure, displacement and other physical quantities. Setting parameters will be memorized when power off. Suitable for detecting the speed of every kind of motors. Over-range display: the thousand unit display "1" or "-1", the last three do not show. Product Specification Display typeLED display VoltageDC8-24V Current30mA Measurement range10-9999rpm Accuracy0.1% Clear zero timeAbout 10s Display refresh rate>3 times/sec Sizeabout 80*25*40mm(L*W*H) Installation sizeabout 76*39mm LED colorred/blue Detected objectsMagnet. Detection range1mm-10mm. Proximity output current20mA(For the sensor). Operating temperature-10 to 60C. Sensor size60 x 10mm Sensor wire length1.2M Magnet10x2mm Package Included 1 x LED Tachometer 1 x NPN hall proximity sensor 1 x Magnet