This pair of nipple suckers are ideal for anyone desiring real nipple suction. Simply place the base of the sucker firmly against the nipple to create a seal, then twist the easy grip control cap clockwise until you have reached the desired level. These sturdy nipple toys are very strong. To release suction, just turn the cap backwards. These ultra powerful suction devices can go anywhere your imagination desires. Measurements: 4 in. total length, 1.7 in. inner diameter.