Originally I had the aluminum cups that were not double lined and they did not keep anything cold and all they did was sweat all over everything. We were going to Hawaii and I knew I just had to find a better solution. So I gave these a try. OMG!!! The are the BEST cup ever. We would put water, soda, flavored water - whatever - in the cup in the morning with some ice. Then drive around all day and leave the cups in a car that was over 100 degrees and by the end of the day the beverage was still ice cold and the ice had not even melted all the way. Absolutely amazing. You just can't go wrong. Easy to drink from, no sweating - it is perfect. I am keeping these babies under lock and key when our son comes over and wanders off with the hodge-podge of cups and glasses we have, never to be seen again.