TACHOMETER The Extech High Precision Contact Tachometer is used for contact RPM measurements plus linear surface speed measurements in ft/min or m/min. The large 5 digit LCD display makes the data easy to read and the built-in memory recalls the last min/max value stored. The meter is autoranging with 0.05% accuracy, and contact measurements frm 0.5 to 19,999rpm. Accessory wheels enable the tachometer to measure linear surface speed by simply contacting the rotating object with the sensor tip. Specifications:  Range: 0.5 to 19,999rpm; 0.2 to 6560ft/min; 0.05 to 1999.9m/min Resolution: 0.1rpm (0.5 to 999.9rpm); 1rpm> 1000rpm Accuracy: +/-(0.05%rdg +1d) Sampling time: 1 sec> 6rpm Dimensions: 6.7 x 2.8 x 1.5" (170 x 27 x 37mm) Weight: 9.2oz (260g) Warranty: 1 year