A cylinder is placed around the penis. A hose is connected to the pump which evacuates air from the cylinder. As the air is removed from the cylinder, the penis is pulled further into the cylinder and towards the walls of the cylinder, making the penis larger. The pumps do have medical uses for men who suffer from impotency. Pumps can be used to obtain an erection, maintaining it erect with a cock ring, removing the pump to engage in sexual intercourse.