The Metrix Plus 1 RPM Digital Tachometer is a Photo-Contact Tachometer. The 1 RPM Digital Tachometer has 2 modes of measurement, which are photoelectric and contact mode. The Metrix Plus 1 RPM Digital Tachometer can be used to measure rotational speed in RPM. The 1 RPM Digital Tachometer comes in a box with a user manual. The device is recommended to be used at a normal temperature up to 50 °C and lowest in 0 °C. The device is sturdy and does not get damaged if stored within the recommended storage temperature condition of -20 °C to 60 °C and away from strong temperature fluctuations. Product Specifications: Manufactured by: Metrix Plus Country of Origin: India Product Code: TM 4005 Measuring Range Photo: 2.5 - 99,999 RPM Contact Range: 2.5 - 19,999 RPM Linear Rolling speed: 0.05 - 1999.9 m/min Surface speed: 0.2 - 6560 Ft/min Accuracy: ± (0.05% + 1word) Power: AA x 4 batteries