Fluke 931 Digital TachometersFluke 931 Contact and Non Contact Dual Purpose Tachometers The Fluke 931 tachometer is a handheld tachometer, which integrates the contact and non contact speed measurement functions and can accurately measure the revolutions per minute (RPM) or surface speed and distance. Fluke 930 is equivalent to a Fluke 931 with minimum configuration. With only the non contact measuring function provided, it's more affordable and offers consistent quality.