text: The Flettner rotor inspired Sigurd Johannes Savonius to invent a spinning ventilation device after a collaboration between the two inventors. Anton Flettners company Flettner Ventilator Limited acquired Savonius patent and still sells them in the United Kingdom. The devices are often referred to as "Flettner ventilators" even though the mechanism more closely resembles a Savonius wind turbine, which was a 1924 invention that resulted from the same collaboration.