461895 Combination of contact (0. 5 to 19,999 RPM) and non-contact (5 to 99,999 RPM) types for use in almost all tachometer applications. Visible light is used for non-contact measurements up to 6in (150mm) from the object. Wheels for measuring linear surface speed (0.2 to 6560 ft/m; 0.05 to 1999.9 m/m) or RPM, 4 AA batteries, 23in. (0.6m) reflective tape, and carrying box are included.Contact and non-contact RPM measurements using a visible light beam