Features Good stability, high precision and strong anti-interference ability,Easy to use, Suitable for novice or professional use. The external appearance adopts standard size and convenient to install,high strength, high cost performance. Input pulse signal: NPN/PNP open collector ,contact switch, contactless switch, level pulse. Input signal voltage: low level: -30V -0.6 V, high level: 4-30V. Measuring range: frequency: 9999Hz, 999.9 HZ, 99.99 KHZ, automatic switching selection,More professional and practical. Descriptions: Digital LED tachometer adopts the latest A/D conversion chip and the high stability benchmark IC, adopts electronic chip component, reasonable circuit design. It can be applied to the measurement of voltage, current and external sensor to measure temperature, pressure, displacement and other physical quantities. Suitable for all kinds of digital instrument display. Specifications: Measurement accuracy: ±0.1% Display mode: 0.56"LED Display refresh rate: >3 times/sec Working power supply: DC8-24V, 30mA, measurement range: 10-9999RPM Hall proximity switch : magnetic Appearance size: 80 x 42 x 25mm/3.14 x 1.65 x 0.98inch LED display(Optional): red, blue Weight: 80g(red),105g(blue) Overrange display: the first one shows "1" or "-1", and the latter three do not show Package Included: 1 x Tachometer 1 x Hall NPN proximity sensor Package List