Store, freeze and warm breast milk, at home or on the go. 6 oz leak-proof breast milk storage bags, pre-sterilized with hygienic double-seal zipper. Available in 100 and 200. Elvie Breast Milk Storage Bags are packed with useful features to ensure your liquid gold is stored safely and efficiently. Made from a thick, tear-proof material and reinforced with a double-seal zipper to prevent leaks.