Digital tachometer is a digital device that measures the speed of the rotating object. It is an optical encoder that identifies the angular velocity of a rotating shaft or motor. It is commonly used in automobiles, airplanes, medical and instrumentation applications. Specification: Display: five 31mm word superb large LCD screen Test range: 2.5RPM ~ 99,999 RPM (r / min) Resolution force: 0.1RPM (revolutions / minute) (2.5 999.9RPM) 1RPM (rev / min) (1000RPM) Measurement Accuracy: ± (0.05% 1 words) Sampling time: 0.8 seconds (60RPM above) Effective measuring distance: 50mm to 200mm (LED light source) Package includes: 1 x Digital Tachometer DT 2234A