A penis pump is an airtight and cylindrical tube that can be slid around the penis. The penis pumps from this category are put into operation by means of a hand pump. By squeezing this pump, the tube is evacuated. The penis pump increases blood flow to the penis and also ensures that the blood is retained . This ensures a firmer and harder erection that usually lasts for about half an hour. Most penis pumps in this category are transparent so that you have a good view of the penis when it is growing. In addition, the toys have a vent valve that, when pressed, allows the air to escape from the cylinder.