Cools only superficially

I had hoped from the cuff that it can cool rooms warm cans relatively quickly to drinking temperature. Unfortunately, this is not the case.
Although the cuff was 2 days in freezer, it could not cool down significantly, a can of beer.
The Büche feels cold to the touch although, while drinking one notices but that the cooling was carried out only on the surface.
In summer you can completely forget the cuff at least outdoors, here is that the metal box the only thing that's cold.
In addition, the cooling effect of the sleeve is just enough so for a rifle, who has so guests need more.

Already in the refrigerator chilled cans remain the drink cold for longer, a purchase does this but not necessary.