The 4-pack of 250 ml storage jars from Miniland is ideal for freezing and thawing breast milk in the same airtight container. Other liquids such as juices and soups as well as solid foods such as porridge or snacks can also be stored safely. The jars have a scale for measuring quantities and a labelling field for the date and contents to keep track of feedings. The microwave and freezer safe containers can be used directly for heating in any bottle warmer, microwave or bain-marie - convenient for at home and on the go. 100% BPA-free for maximum safety.