The Dual Breast Exerciser features a suction pump containing 2 cups that perform squeezing and sucking of nipples. This causes firming of your nipples thus enhancing sensations. You can easily control how much suction your breasts want by using a manual pump. Each cup is 4.5 inches in diameter which means it will fit any breasts. Hygienic and soft materials will take care of your gentle nipples. This sex toy is also provided with quick release valve. It is easy to use, easy to control and easy to clean it.