A beer koozie [koe-zie] is a fabric or foam device that is designed to insulate a beverage can or bottle. It began as a marketing tool. The primary use of a beer koozie is to keep one’s hand warm while keeping the beer cold.
A secondary use of a beer koozie is to easily identify one’s beverage from another. Many different companies have used the koozie as a promotional giveaway because it is not only inexpensive to manufacture, but its frequent use is more likely to bring the company’s name to a household presence. Originally this logo or image was screen-printed on a round foam cylinder with a foam base (generally a hole is provided in the base to alleviate creation of a vacuum). A koozie can be made from many materials like neoprene, polyester or open cell foam.
The Daily Omnivore 