Keep your cups in tiptop condition. Kids love our Munchkin cups so make sure you always have some replacement valves on hand in case one comes loose or you lose it during washing. These patented onepiece easy to clean silicone valves fit all Munchkin spillproof cups. They make drinking easy because the liquid flows through the valve only when your child takes a sip. That's why moms love our cups almost as much as their kids.