"They DO work..."
15 April 2009
... when used with an insulated bag. We bought these along with an insulated sandwich bag. We used them all last summer to take lunch to the beach on the hottest days (in the UK anyway!), and our sandwiches and boxes of juice were still practically fridge-cold by lunchtime, 4-5 hours later. Use them to extend the length of time an insulated bag will keep things cool for. I can imagine that just put in a normal plastic box they won't stay frozen long at all - after all, they're not that big. But in an insulated bag or cool box they're great. The gel doesn't go solid when frozen so they're still pliable, unlike some other products that just turn into a block of ice.