Really a great eye-catcher at parties, but extremely impractical. Not only that melt the glasses quickly, above all, they are very hard to get out of shape. Although warm water helps, but just shortened the life of the glasses, which are really leaking after a few minutes just at the bottom or it is already at the leaching out of the mold. Unlike them, however, are hard to solve out of it, and the other day one of the 3 of 4 blocks is broken me when I tried the glasses "rotate" through the (warmed) hard plastic form elicited.
Jedochsie are really cheap and I use that in comparison to large ice cubes but hollowed glasses also like as ice, both to use and just like that.