Menstrual cups are reusable products made of silicone or rubber. Because they are flexible, they are inserted like a tampon. However, they collect rather than absorb blood. Menstrual cups work by creating a seal (slight suction) and catching your menstrual fluid. The cup sits directly below the cervix and is held in place by the pelvic floor muscles. When inserted correctly, they don’t leak, and you won’t even notice it’s there.  See our menstrual cup diagram. • The uterus is the reproductive organ that creates and sheds a lining that is your period. • The cervix is like the ceiling of your vagina. The cup can’t go further than this upper limit. • The vagina is the internal tunnel where menstrual fluid flows from to your external vulva.