UT373 is a digital non-contact tachometer used to measure rotation speed of motors and other machines.This device is to display results in RPM or revolution count. UT373 is to safely measure rotational objects through a non-intrusive . 1. Auto range 2. Up to 99999 display; overload diaplay, OL 3. RPM measurement and revolution count: RPM measurement-Range: 10.0-9999.9RPM / Resolution: 0.1/ Accuracy:+/-(0.04%+2) RPM measurement-Range: 10000-99999RPM/ Resolution: 1/ Accuracy:+/-(0.04%+2) Counting measurement-Range: 0-99999 counts/ Resolution: 1/ Accuracy:+/-1 4. Max/Min, data hold 5. Singal trigger/laser-on indication 6. Low battery/auto power off indication 7. LCD backlight Refresh rate:1s to 7s ( 120rpm for 1s) Sensor type:Photodiode and laser-tube distance:50mm-200mm Measuring angle:+/-30degree from perpendicular Drop test:1m Power supply: 3 x 1.5v AA battery (not included) colour:Red+gray Material:ABS size:120 x 53 x 34mm Package Contents: 1 x UT373 Mini Tachometer (not including battery) 2 x Reflective strip Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.