The model is manufactured by Meggit, and is an aerospace speed probe that generates an electrical signal. The frequency of the electrical signal is equivalent to the speed of the engine shaft. The unit is integrated with one up to two coils, and a rare-earth permanent magnet.
In turning equipment, the sensing surface of the unit faces the phonic wheel. As the magnetic flux differs in density with the passage of each tooth, these changes produces an alternating voltage in the coil enveloping the permanent magnet, the frequency of which is a function of the shaft speed.