Neoprene is a material that wet suits are made out of. the material is designed specificaly to insult what ever it is covering whether it be a body or a koozie. The neoprene will be able to keep you warm if you are in cold water and cold if you are in hot water. It will do the same for you beer. If your beer is cold it will keep it cold if you beer is warm it will keep it warm. Of course, not many people like warm beer.
An interesting fact about Germany. They never put beers in the fridge. Most beers are stored in the trunk of a car or in the cellar where the air is always cold.
Because the material is rubbery a Full color image does not print without melting the neoprene. However multi-color ink designs are most definitely available if you would like. Most things do haven’t look better in single ink.