Non-contact rpm measurements to 99,999rpm with integral light beam. Extech 461893-NIST Tachometer Photo allows you to make non-contact RPM measurements (5 to 99,999 RPM) of rotating objects by pointing the integral light beam (6 in. target distance) at reflective tape placed on the object to be measured. The memory button holds last reading and recalls min/max readings display. With NIST Calibration.