Nuby No-Spill Drinking Cup Review

My child was having a difficult time transitioning from the bottle to a sippy cup. He just couldn't get the hang of sucking through the top. I saw the Nuby cups at Wal-Mart and decided to give them a try. My child accepted the  cup right away. Because the silicone top is soft like a bottle nipple, the cups are easier for children to learn to use. The only negative I've found is that my child chews on the top and causes the vents to tear causing leaks. I've had to buy several replacements since we started using them. I wish Nuby would sell just the silicone tops so I didn't have to purchase a whole new cup each time.