The perfect solution for the child that is ready to stop drinking from a spout. Like many of our other patented Nûby silicone feeding and drinking items, the Vari-Flo Valve allows the child to control the liquid's flow rate. With its Flip-It sliding motion, it's also the perfect cup for travel. Just slide open to sip, or slide shut to protect the straw from dirt or damage for future use! Parents never need to worry about any messes with a Nûby No-Spill Straw: No Spills! No Leaks! No Mess.1 per pack. Assorted Colors.