The cylinders work great, but I ended up getting about 24 more of them seperately at Target they are easier to deal with and freeze than the bags. Plastic bottles and component parts become brittle when frozen and Medela breast milk feeding and storage set break when dropped. Write the date on a piece of tape and place on the bag or bottle. Unique lids helps mom quickly identify which bottle to feed next Made without BPA: Do not let child take bottle to bed or self-feed for long periods of time. Storing breast milk because it is the best for your baby Breast milk is the ultimate all-in-one nutrition for your baby. Find in a store near you here.