It is to deepfreeze breast milk and keep it fresh,you may carry it and feed baby at any moment . Specifications: 1) Size: 4x120ml feeding bottle. 2) Cool-storage terms: to refrigerate the chill box for more than 4 hours inside the refrigerator or chill cabinet. 3) Chilled conditions: to deepfreeze for 10 hours at room temperature. For more information about our company, welcome to visit our website: http://www.deluxe-breastpump.com/, there are clear photos, good video and detailed specification on it.