Good stability, high precision and strong anti-interference ability. The outer appearance adopts the standard size and easy to install. Input pulse signal: NPN/PNP open collector, contact switch, non-contact switch, level pulse. Input signal voltage: low level: -30V -0.6V, high level: 4-30V. Measurement range: frequency: 9999Hz, 999.9HZ, 99.99KHZ, automatic switching selection. Specifications: Measurement accuracy: 0.1% Display mode: 0.56" LED Display refresh rate: >3 times/s Working power supply: DC8-24V, 30mA, measurement range: 10-9999 rpm Detector proximity: magnetic Appearance size: 80 x 42 x 25mm / 3.14 x 1.65 x 0.98in LED display (optional): red, blue Weight: 80g (red), 105g (blue) Overflow display: the first one shows "1" or "-1" and the last three do not show Precautions: 1. Connect the plug correctly according to the wiring diagram 2. Should avoid strong electromagnetic interference and it is better to use shielded wire or double-stranded wire to measure the 3 conductors. The count signal of the counter and the switch of the reset signal or circuit input should be as close as possible to the counter terminal to make the signal line as short as possible 4. Avoid using cables such as Note: This does not include other things, the color is based on the first picture, and other pictures only show the effect In Due to the differences between different monitors, the picture may not reflect the actual color of the item. Due to manual measurement. Please allow deviation. THANKS becomeveryrich