TheseTwist Cups can be applied to any body part. With a rotating movement the cup turns into a suction device. The more you turn, the stronger it sucks. A wonderful feeling when it's put on the nipples by the insanely good suction power of these twisted black cups that you can adjust yourself of course.
Inner Diameter: 21 mm.
Use a lubricant at the bottom of the cylinder to get a better vacuum.