Have good stability, high measurement precision. Strong anti-jamming capability. Setting parameters be memorized when power off. With a standard size, easy to install. Suitable for detecting the speed of every kind of motors. Specifications: Power requirement: DC 8-24V Measure range: 10 ~ 9999RPM Error range: 0.1% Clear zero: Automatic Clear zero time: About 10s Refresh frequency: 0.2-0.5S(120-1200RPM),0.25-0.06S(2400-9999RPM) Response frequency: 100HZ. Measure indication: (RPM Less than 5000,2),(RPM more than the 5000,3) Sign: NPN 5 wires normally open. Display: 5 x 2cm LED Detection range: 1mm-10mm. Proximity output current: 20mA(For the sensor) Operating temperature: -10 to 50 Celsius Sensor wiring: brown(Power+), black(Test+),blue(signal) Colour:black Material:plastic Package Contents: 1 * Tachometer RPM Speed Meter 1 * Hall Proximity Switch Sensor NPN Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.