Penis pumps consist of a hollow cylinder, typically made of clear plastic or glass that is completely open at one end and has a valve or tube connected to the other end. The tube is connected to a bulb or some other mechanism by which the air can be drawn out of the cylinder after the penis is insterted, thereby creating a vacuum.

Pumps for Pleasure
Pleasure pumps are designed to simulate the sensations of oral sex, using the vacuum created from the pump as well as rotating pleasure beads, cyberskin linings and even rotating shafts.

Pumps for Penis Enlargement
Penis enlargement pumps are designed to stretch, lengthen and thicken the shaft of the penis by drawing excess blood into the penis and holding it there with the vacuum seal. Typically, these pumps will also come with an instructional manual explaining how to get the maximum results.