requirement:DC 8-24V Measure range:10 ~ 9999RPM. Error range: 01% Clear zero:Automatic . Clear zero time:About 10s. Refresh frequency: 02-05S(120-1200RPM),025-006S(2400-9999RPM). Response frequency:100HZ. Measure indication:(RPM Less than 5000,2),(RPM Greater than 5000,3). Sign:NPN 5 wires normally open. Display: 4 red LED. Tachometer size:79 x 42 x 25mm. Panel cutout size:76 x 39mm. Hall proximity model:NJK-5002C . Detected objects: Magnet. Detection range: 1mm-10mm. Proximity output current: 20mA(For the sensor). Operating temperature: -10 to 60C. Sensor wiring:brown(+),black(Test+),blue(signal). Sensor size: 60 x 10mm. Sensor wire length:12M Magnet:10x2mm Function selection: 1Reset or manual reset on . 2Store the data (no ). Material:metal+plastic package include: 1 x Red LED tachometer 1 x NPN hall proximity sensor 1 x magnet Note:Light and different displays may cause the color of the item in the picture a little different from the real thingThe measurement allowed error is +/-1-3 cm.