The Size Matters Nipple Boosters can enlarge and stimulate your nipples. Suction and increased blood flow to the nipples increases sensitivity and pleasure. Simply place them over the nipples and squeeze the bulb. The nipple suckers will create a vacuum sensation when you release your fingers. After you release the nipple boosters they will stay in place and you may enjoy hands free stimulation! Measurements: 6.7 cm long, 2.5 cm opening inner diameter, 4.3 cm bulb diameter Material: Rubber Color: Black