Evenflo's Advanced Breast Milk Storage Bags are uniquely designed to help you collect, store and freeze your breast milk. These leak resistant bags are made from a military grade material and feature Evenflo's SafeZip Dual Track Zipper and enhanced wide side seals, so you can feel confident that your pumped milk is safe and sealed securely until you need it. The special gusseted bottom design allows the bag to stand on its own when filling your breast milk storage bags, making it easier to transfer pumped from collection bottles, reducing unwanted spills. And storage is easy! You can freeze these bags standing upright or lying flat to save space, or place them in the refrigerator to use during your next feeding. These breast pump bags also freeze and thaw quickly, saving you time when preparing breast milk for your little one. As an added bonus, the Advanced Breast Milk Storage Bags now come in a resealable bag, which means you can take them with you wherever you go. These breast milk storage bags are also 100% free of BPA.