The NUK Breast Milk Storage Bags are very useful for lactating mothers. These self-standing milk storage bags are freezer safe so that you can save milk for your baby to be fed when you are not around. They come in an innovative design and a leak-proof double zipper seal that make the process much more efficient. The baby milk storage bags come available in 25-count, 50-count and 100-count packs, and they easily fit most disposable bottle holders. The bags can go into the freezer standing up, and the volume markings on the front allow you to see how much is in each bag. They thaw easily, making meal time quick and easy. These freezer storage bags also feature a space to write the date on the bag so that you know how old the milk is.