TAKE YOUR NURSH TO THE NEXT LEVEL. When your babys ready to graduate to a straw cup, these Silicone Straw Conversion Tops are all you need. Designed to fit perfectly on your 8-ounce NURSH baby bottles, the silicone straw turns your existing bottle into a kids straw sippy cup. The unique design of the silicone straw combines with your baby bottles existing silicone pouch for drinks that only touch 100% silicone. The rotating cover and valved straw included in this conversion top keep the drinks inside the cup and off of your kid. Whats that? You only have 4-ounce NURSH bottles? Go ahead and carefully cut the straw down to size; we love a good parenting hack!