Koozies

I was holding a can that had a koozie on it, and I realized that the koozie was preventing the drink inside the can from becoming warm (or at least, it was slowing down the process).  Heat transfer is due to a temperature gradient between two bodies.  Heat transfers from the body with the higher temperature to the body with the lower temperature. The koozie was preventing heat to transfer into the can due to the temperature difference between the cool drink and the warm air.