The ColdKit's ice pack consists of 8 small squares filled with distilled water.   To prevent puncturing, store the ColdKit in the freezer.  If one square is punctured, the other squares will still work and you can continue to use the ice pack.  Here are some useful tips in using your ColdKit:You should freeze the complete ColdKkit overnight before using it. Remove the ColdKit from the lunch bag as soon as it comes home to prevent excess moisture inside the bag.Wash the ice pack's fabric sleeve when needed either by hand or machine.Make sure to thoroughly dry the ice pack's fabric sleeve before using it again.Wipe clean the ice pack as needed.We recommend treating the thawed ice pack with extra care to prevent ripping and puncturing.