The Fairmount Cup Counter Anemometer unit is housed in a cast gunmetal box with a top cover. Incorporated in the front is a window through which the digits can be observed. The stainless steel vertical spindle carries the cup assembly and drives the lay shaft by worm and wheel, the worm being pinned onto the spindle.

Six digit wheels are mounted on the lay shaft, two are red with white digits registering 1/100 and 1/10, the other four wheels are black with white digits. Five multiplier wheels are fitted to a parallel lay shaft allowing the digit wheels to be indexed upwards for a revolution of the one below it. Thus a total of 9999.99 can be read as a maximum. The unit can be calibrated to read knots, m.p.h., and km/hr necessitating a change of worm and wheel configuration.

The cup assembly mounts on the top of the spindle and revolves anti-clockwise viewed from above. A socket tapped 1/2″ BSP female below the casing is used to mount the counter.