The cylinder fits over the penis and the pump is attached to the end, the sleeve fits snugly over the base of the penis shaft creating a tight seal and vacuum. Using the hand pump, which has an easy release valve, the air is gradually sucked from the cylinder and the penis fills with blood making it ‘grow’. The cylinder has a measuring device on the side so you can keep track of the size as your penis grows, it is a very effective pump that is able to assist guys in enlarging their penis and also pumping more blood into their penis which helps to enhance orgasms