Nuby's clik-it range of cups offers leak-proof technology that you can see and hear, so parents won't have to worry about spills and leaks! As you twist the lid into place, it "clicks" So you know it's securely attached to the cup base. Nuby's clik-it designer series cup has a soft silicone spout that is gentle on children's tender gums and emerging teeth. The spout is also designed to prevent drips and spills. Nuby knows little ones are animated and active, even while holding (or sometimes dropping) their drinks. That's why we designed our cup spout with a pressure-sensitive TOUCH-FLO valve. This clever valve helps regulate fluid intake as children drink. As children suck ON the spout, it opens to allow liquid to flow through. When sucking action ceases, the spout closes, ensuring a leak-resistant cup. Whether your child sits still while sipping, or frequently knocks over and holds their cup at an angle, nuby has you covered.