Large easy to read (99,999 count) LCD display. Autoranging with 0.1 percent basic accuracy. Hold button freezes displayed reading. Ergonomically designed and pocket sized housing with protective finger guard. Easy to operate by simply contacting the rotating object with the sensor tip and read. 461750 Contact model with surface wheels enable tachometer to measure linear surface speeds in ft/min, m/min, and yd/min. 461700 Non-contact integral light beam model with ideal measurement range up to 6 in. (150mm) distance. Complete with 9V battery; 461700 includes reflective tape and 461750 includes surface wheels.