I bought this for my daughter who is 10. She swims competitively and I wanted an alternative period option to tampons for her. I saw that someone else had also bought this for their daughter so I tried it. Her flow can get pretty heavy i think considering she just started. 2-4 regular pads during the school day. We used this for the first time at a swim meet. It ended up being kinda loose but we made it through the day (8 hours) without leakage. I brought a million dark colored towels and a lot of extra clothes just in case but it didnt show signs of leaking while she wasnt covered in a towel. After that we bought a size smaller and now we use it every time she has her period. We have not had problems and we've been using them for 7 months. We now have 3. I also have a bikini bottom for myself. It works but I've only used it while my flow is not super heavy.