Nuby's Clik-It Flex Straw cup will stop parents from worrying about spills and leaks! The lid "clicks" when twisted into place, so you know it's securely attached to the cup base. Nuby's Clik-It Flex Straw cup has a soft silicone straw designed to prevent drips and spills. Little ones are animated and active, even while holding (or occasionally dropping) their drinks. That's why Nuby designed a cup straw with a pressure-sensitive TOUCH-FLO valve that helps regulate fluid intake as children drink. As children sip on the straw, the valve opens and allows liquid through. When sipping ceases, the valve closes, ensuring a leak-resistant cup. Whether your little one stays still while sipping, or prefers to keep on the move and hold their cup at an angle, Nuby has you covered. The Clik-It Flex Straw cup holds 10 ounces (300ml) of liquid, keeping little ones happy and hydrated. With a convenient 3 pack of Clik-It Flex Straw cups, little ones never have to go without their favorite cup!