This tachometer is a high-quality instrument for measuring rotational speed (RPM) with a wide measuring range and high resolution. It features high-precision measurement, fast measuring time, and a long detection distance of up to 500 mm (20 inches) with laser. This tachometer is very easy to use by applying a reflective mark (included in the package) to the target object and then aiming the mark by laser beam. Specifications: Test range: 2.5 rpm ~ 99,999 rpm (RPM) Resolution: 0.1 rpm (revolution/minute) (2.5 ~ 999.9 rpm) 1 rpm (revolution/minute) (above 1,000 rpm) Measurement accuracy: (0.05% + 1 word) Sampling time: 0.8 seconds (above 60 rpm) Effective measuring distance: 50 mm ~ 500 mm (laser light source) Time base: 6 MHz crystal oscillator Data storage: 20 groups Range selection: automatic switching Power supply: single 6F22 9V battery Power consumption: about 35mA Memory: maximum value, minimum value and last measured value. Package size: L136 x W98 x D400mm Weight: about 160g Package Contents: 1 x New Digital Photo Laser Tachometer Non-Contact Tachometer 1 x English Manual 1 x Carrying Bag