Features: Easy to use, non-contact measurement. With data hold, maxminavg measurement function. Automatic shutdown after 10 minutes of no operation and can be cancelled auto power off function manually. High and Low alarm limit setting function. The upper and lower alarm limit is settable. The screen will emit red background light when over upper and lower limit. Oversize LCD display screen with white backlight, long press the backlight key more than 2s to turn it on. With temperature and humidity measurement function. Analog bar scale indication and low battery indication function. Specifications: Model: TA501A Measuring Range: 2.5RPM ~ 99999RPM(rpmmin) Resolution: 2.5RPM ~ 999.9RPM (0.1RPM); 1000RPM above (1RPM) Accuracy: +- (0.05percent reading + 1 digit) Maximum display: 999999 Ambient Temperature Range: 0 ~ 60 celsius Accuracy: +-2 celsius Measuring Effective Distance: 50mm ~ 500mm Sampling Time: 0.8 seconds (over 60 rpm) Automatic Shutdown: about 10 minutes (can be manually turned off) Operating Environment: -10~50 degrees C, relative humidity up to 80percent , indoor altitude less than 2000m Storage Environment: -10~50 degrees C, maximum 70percent relative humidity (take out the battery) Display Size: 37 x 41mm Power Supply: 3 x 1.5V AAA (R03LR03) (Not Included) Material: ABS Item Size: 15.2 * 5.5 * 3.3 cm 5.98 * 2.16 * 1.3 inch Item Weight: 115g 4.05oz Package Size: 22 * 9.5 * 5.5 cm 8.66 * 3.74 * 2.16 inch Package Weight: 240g 8.46oz Package List: 1 * Tachometer 2 * Reflective Paper 1 * Cloth Bag 1 * User Manual (English)