Milk being consumed is good. Air being consumed is not. Our revolutionary NURSH bottle features a 100% silicone pouch that collapses as your little one drinks, without allowing gas-inducing air back in. Instead of throwing it away after use, simply wash It out, let it dry and use it again (and again, and again again). because it's 100% silicone, our pouches are made without nasty toxins like BPA and PVC and can be frozen, boiled, microwaved and used with sterilizers.