Medela’s breast milk storage bags allow for easy transport, storage and warming of mother’s milk in these convenient, ready-to-use storage bags. Constructed from a durable, double layer material (to preserve and protect the breast milk nutrients for long term storage) and built-in double zipper seal to keep your breast milk safely stored in the fridge or freezer. For added convenience the bags are self standing and come with a large write-on area so you can track the date and time you pump. Made without BPA