The ring (brand name: NuvaRing) is a small, bendable ring that you insert into your vagina. (It kind of looks like one of those jelly bracelets from the 80s, but it feels a tiny bit stiffer.) You leave it in place for three weeks at a time, then take it out for the fourth week. The ring works by giving off hormones that prevent your ovaries from releasing eggs. The hormones also thicken your cervical mucus, which helps to block sperm from getting to the egg in the first place.