A vacuum chamber is provided with a drive region having outside diameter threads and a longitudinal guide slot. An annular collar carries inside diameter threads for mating with the vacuum chamber threads such that the collar is longitudinally moved relative to the vacuum chamber by user rotation of...http://www.google.es/patents/US5624378?utm_source=gb-gplus-sharePatente US5624378 - Pumpless vacuum generation for augmenting male potency
Pumpless vacuum generation for augmenting male potency
