Sanpometer DT2235A digital contact tachometer (rpm gauge or revolution counter or rev-counter)/ surface speed meter. Features and specifications: 5 digits 18mm (0.6") white backlight LCD; Accuracy: ±(0.05%+1 digit); Sampling Time: 0.5sec (over 120rpm); Range Select: Auto-ranging; Memory: Max. value, min. value, last value, can store 96s data; Power Consumption: Approx 45mA; Time Base: 6MHz Quartz crystal; Time Base Accuracy: 10x10-6(0~50°C); Measuring Range: Contact Tach: 0.5~19,999rpm, Surface Speed: 0.05~1,999,9m/min; Resolution: Contact Tach:
0.1RPM(0.5~999.9RPM), 1RPM(over 1,000RPM), Surface Speed: 0.01m/min(0.05~99.99m/min), 0.1m/min(over 100m/min); Battery: 4x1.5V AA size battery.