Portable coolers help the things kept inside them to stay cool because of the insulation in them that prevents the ice placed inside to remain in the frozen state for longer periods. Insulation in an ice cooler is made from plastic or foam and slows down the warm air and prevents warm air from traveling around the enclosed space of the box.
Ice cubes in a cooler can stay in their frozen condition for a day or two, while if block ice is used it can last for 5 to 7 days. You can also use dry ice to lower the temperature in these coolers. Your cooler will remain all the more effective if you pre-chill the food and drinks that you store in them. The ice must be put in only after you have filled it with whatever you want to carry with you.