Medela Breast Milk Storage Bags 25 piecesThe double walled bags have a leak proof double zipper, ensuring safe freezer storage. The bags are hygienically pre sealed and the flat shape of the bags makes it quick to thaw breast milk. The large area for labeling and dating the bags makes it easy to keep track of your stock of milk. The bags are made from food grade, BPA free material. Features and Benefits: Lays flat for space saving and requires less storage space than conventional bottles.