The Tulips Premium breast milk storage bags come in a package of 20 units in a box. The bisphenol A-free bags have undergone a sterilization process, making them sterilized and ready for immediate and safe use. The bags are especially strong and the milk can be collected and stored without fear of drips and leaks. The bags with the flat base are designed in a way that allows them to be placed in the refrigerator or freezer, for maximum convenience and the best results. On the packaging is a dedicated area for easy writing of the pumping date. The milk can be stored in the refrigerator for up to 24 hours, or in the freezer for up to three months.