Useless product. Does not significantly cool down a beverage and does not stay cool longer than a half hour or so.Was hoping they would work. Didn't seem to do much at all when I first tried them so I took out a thermometer to see what was going on. Put them in freezer. They got down to 7 degrees. Took a beer from the refridgerator and put it in the holder. The beer was at 39 degrees. Let it set on counter for 20 minutes. Measured temps again. Beer was now 34 degrees and the sleeve was now 34 degrees. Not a big improvement. Tried to drink beer while it was in sleeve. Awkward. Beer kept wanting to slide out of bottom. Slowly drank beer, hardest part of experiment!, within 10 minutes the sleeve was up to 50 degree from my holding it.Also tried same with a beer at room temperature. Beer started out at 65 degrees. Sleeve started out at 7 degrees. After 15 minutes both the beer and the sleeve were at 57 degrees.Cans and bottles behaved about the same.Just my personal experience with them.