Tachometer is used to detect rotate speed, linear velocity or frequency of motor.It can be widely used in motor, fan, washing machine, textile, automobile, airplane, ship and other industries. Features: Adopt the latest microprocessor technology and laser technology. Wide measuring range and high resolution. Battery low power indication, LCD backlight display and auto shutdown after 60s. Oversize screen LCD display, with clear indication. Hold the Maximum/minimum/average/last measured value. Solid and delicate structure, durable for use. Specifications: Display: LCD Backlight  Unit: RPM Measuring Range: 2.5~99999RPM Resolution Ratio: 0.1RPM(2.5~999.9RPM); 1RPM(1000~99999RPM) Measuring Error: +/-(0.1%n+5d)RPM; 0.1RPM(2.5~999.9RPM) +/-(1%n+5d)RPM; 1RPM(1000~99999RPM) Laser Power: 2-5mW Sampling Ratio: Once/second Measuring Distance: 50-500mm Auto Shutdown: After 60s without any operation Power Supply: 2 * 1.5V AAA Batteries (Not included) Operation Environment: 0~50°C  / 32~122°F; 10~90%RH Storage Environment: -10~80°C  / -14~176°F; 10~75%RH Dimension: 55 * 29 * 125mm / 2.16 * 1.14 * 4.92in Weight: 98g / 3.47oz Package Size: 15.5 * 8 * 4cm / 6.1 * 3.15 * 1.57in Package Weight: 165g / 5.84oz Package List: 1 * Tachometer 3 * Silver Reflective Tag 1 * User Manual (English)