1. [Keep food and drinks chilled] Use a cooling backpack to keep food and drinks chilled and fresh for 18 hours. It's perfect for lunch bags and outdoor activities. 2. [Keep breast milk fresh] Bring fresh breast milk to your baby to help the baby grow better. No more carrying multiple backpacks around! 3. [Storage space] The ice packs can fit into almost any imaginable lunch box or cooler, and take up less space for food or drinks. 4. [Reusable] Unlike ice cubes, ice packs don't make a mess when they thaw and can stay frozen longer. When the ice packs start to melt, sandwiches and other food won't spoil. Note: A cooler filled with water can be used after getting 80% cold water, and then place it in the refrigerator for about 5 - 10 hours. Don't fill it with too much water due to thermal expansion and contraction.