They are not like traditional tampons. It works like a suction cup system, effectively blocking the flow for many hours before you have to pour out the cup. Visit the Instead website, it will give you more information. I have used these for many years and you can't feel them when they are placed in correctly. Also they are great if you have a heavy flow. You can reuse the cup by properly washing it out after every emptying, and it saves a whole lot of money, because you can clean it and reuse it for one whole period. You would use a whole box of tampons otherwise, so Yeah these are pretty great.