TACHOMETER Features: Measures rotational and surface speed. Built-in memory. . Digital display. Auto power off function. . Easy to select units and mode functions. Contact and non-contact measurement. . Select rpm using infrared beam or adapter: m/min, m/sec, ft/min, ft/sec, in/min, m, ft, and in. Includes 6 adapters, carrying case, reflective tapes batteries and users manual. .   Spesification: Size    175x60x28 mm (7x2.5x1 in) Weight    250 g (0.55 lb) Safety    CE Accuracy    ±0.02% v. reading ±1 Digit Measuring Ranges rpm    optical 1 ... 99999 min , mechanical 1 ... 19999 min Battery type    2x AA 1.5V Battery LR6 (ALKALINE) or rechargeable