A Menstrual Disc is a small, flexible cup made of medical-grade silicone and instead of absorbing your flow, like a tampon or pad, it catches and collects it - without leakage. Most menstrual discs can stay in for up to 12 hours before being emptied and rinsed. This means you can wear one when you're sleeping, or all day long. You may need to empty a cup more often if your flow is at its heaviest, but you can use the same disc for your heaviest and lightest days. Menstrual Cups vs Menstrual Discs A cup sits in your vagina below your cervix and extends into your canal. A disc, on the other hand, fits back into your vaginal fornix, which is where your vaginal canal meets your cervix.