The German Lorenz cipher machine contained 12 pinwheels, with a total of 501 pins
In cryptography, a pinwheel was a device for producing a short pseudorandom sequence of bits (determined by the machine's initial settings), as a component in a cipher machine. A pinwheel consisted of a rotating wheel with a certain number of positions on its periphery. Each position had a "pin", "cam" or "lug" which could be either "set" or "unset". As the wheel rotated, each of these pins would in turn affect other parts of the machine, producing a series of "on" or "off" pulses which would repeat after one full rotation of the wheel. If the machine contained more than one wheel, usually their periods would be relatively prime to maximize the combined period.