Pigeon milk storage bags are pre-sterilized with gamma rays and are BPA-Free. The storage bags contain a leak-proof double zipper seal for added protection. They come with a convenient pour spout for transferring breast milk. These bags keep expressed and frozen milk safe for the baby to feed at a later time. The storage bags contain a waterproof writing tab where the date of expressing milk can be written to keep track of it. The breast milk storage containers come in bundles of 25 bags.