Please note the size of these coolers. A reference picture with a person holding both coolers has been added to aid you in your sizing decision. Cooler Shock introduces the cooler that needs no ice. We’ve created a cooler that has fishnet interior pockets to insert Cooler Shock ice packs straight out of your freezer. This creates great performance and improves usable interior room. Put a pack in each side pocket and one on top for a very cold experience without the bacterial soup! (ice packs sold separately). About the performance guarantee – We guarantee a minimum of 24 hr. cold performance using only 2 Cooler Shock Lg. ice packs. Our test model was on the 24 can cooler was with 8 12 oz. beverages, 6 sandwiches and a fruit side dish. After 24 hrs. at 80 degrees, the interior items were at typical refrigerator temperature of 35 degrees Fahrenheit. The temperature did not rise to 40 degrees until 36 hours had past. The 48 can cooler performed even better using 3 packs with 12 drinks, 8 sandwiches and 2 side dishes.