Most of the sippy cups on the market have hard plastic spouts or rubber spouts. The ThinkBaby built the thinkbaby Sippy Cups with soft silicone spouts. This makes for easy transition from baby bottles to sippy cups. This is a struggle that most parents face in moving to the next stage of feeding. With the thinkbaby Sippy Cup, the little one is already used to the feeling of silicone so making the transition is quite simple. The spouts also feature a cross cut design so the ThinkBaby do not spill when held upside down, which obviously happens quite often. There are also next extra little pieces to lose or clean. The Sippy cup has won numerous awards for both the ability to transform Thinkbaby bottles into the Sippy Cup and for the ease of transition from baby bottle to Sippy Cup. The Sippy Cups are made from No. 5 plastic and therefore can be recycled after use. You may also notice that the ThinkBaby do not use clear plastic windows with our products. The ThinkBaby have found that these windows are made from PET or PVC. It doesn't make sense to take a safe baby bottle and put it up against something that can off gas onto the product.