A menstrual cup is a feminine hygiene product that is inserted into the vagina during menstruation. Its purpose is to prevent menstrual fluid (blood from uterine lining) from leaking onto clothes. Menstrual cups are usually made of flexible medical grade silicone and shaped like a bell with a stem. The stem is used for insertion and removal. The bell-shaped cup seals against the vaginal wall just below the cervix. Every 4–12 hours (depending on the amount of flow), the cup is removed, emptied, rinsed, and reinserted. After each period, the cup should be boiled for at least 5 minutes and stored for use the next month.