These simple and powerful nipple suckers are perfect for anyone looking for some consistent, strong suction. All you have to do is place the base of the sucker firmly against the nipple to create a seal, and then twist the easy grip control cap to create immediate suction. Enjoy a light sucking sensation or twist the knob further to create a serious vacuum. Just turn the cap backward to return the internal plunger to its original position and release the suction when you are ready.Flexibility: FirmMaterial: PlasticBrand: Size MattersSize: 4 Inches