Convenient, pre-sterilized disposable liners. As baby feeds, you can see the soft liner gently collapsing to help prevent air from mixing with milk and getting into baby's tummy. This means less gas and less discomfort for baby ? Pre-sterilized disposable liners for a clean & easy bottle anytime, anywhere. Available in 50 count and 100 count for 4oz and 8-10oz sizes. BPA-Free.