The General Technologies TA300 Smartach D Digital Diesel Engine Tachometer is specially designed for use in diesel engines equipped with a fuel injection pump and individual fuel injection lines. It uses a piezoelectric transducer clamp which is placed on one of the fuel lines for sensing pulses caused by the surge in fuel pressure, and translating these pulses into RPM. Supplied with a 6' sensor cable and a universal piezoelectric sensor clamp suitable for 1/4" and 6 mm diameter fuel injection lines. Different size clamps are also available.