Works as an ice substitute or addition to your ice stash to make sure your contents stay colder for longer. Durable design that is break-resistant to withstand the toughest of tumbles. Perfect chillers for everyday use in lunchboxes, breastmilk bags, bento boxes, and coolers. Great for kids to take to school in their totes, adults to the office or for outdoor camping. Keep your to-go food containers cold and dry. Heavy-duty BPA-free plastic casing for leak-free durability. Stays cold for hours; prepare ahead of time in a home freezer by laying pack flat for 8 hours or more.