461895 has both contact (0. 5 to 19,999 RPM) and non-contact (5 to 99,999 RPM) variants for use in almost any tachometer application. Uses visible light to take non-contact measurements up to 6 inches. (150 mm) from the target. It includes wheels for measuring linear surface speed (0.2 to 6560 ft/m; 0.05 to 1999.9 m/m) or RPM, as well as four AA batteries and a 23-inch length. (0.6m) reflective tape and carrying case.