... used to test the rotative velocity ,surface speed or frequency of motor.Widely applicable to motor, fan, paper-product ,plastics, ... TACH. (RPM) & CONTACT TACH. (RPM , m/min., ft/min). * The use of durable, long-lasting components, including a strong, light weight ABS ... -plastic housing assures elegant shape and ease of use. * Use "USB data output " and "RS-232 data output " with ...