Medela’s signature bottle design allows moms to store their breast milk long-term without losing any of its natural beneficial properties. Compatible with Medela breast pumps for pumping directly into the container (not recommended for use with the Single Deluxe breast pump). Containers have a large panel for writing name, date and time, and easy-to-read volume marks, graduated in ounces and milliliters. The Breast Milk Freezing & Storage – 12 Pack comes with a reusable Quick Clean Micro-Steam bag for daily cleaning of breast milk bottles, nipples and other feeding accessories. All parts that touch breast milk are made without BPA and safe for mom and baby.