High Quality Content by WIKIPEDIA articles! Gas duster, also known as canned air, or compressed air, is a product used to clean electronic equipment and other sensitive devices that cannot be cleaned using water. The can comes with a straw to direct the forceful wind that it can produce. However the straw should be taken out of the nozzle if not in use. The reasoning for this is once the straw has been inserted the compressed air may leak out through the straw. The gases inside the can have been compressed to the point that they have become liquid, and they evaporate before leaving the can, since the valve draws from the top (unlike most aerosol cans, which have a straw that draws from the bottom of the can). Despite the name "canned air," the cans actually contain gases that are much easier to compress into liquids, such as difluoroethane, trifluoroethane, or tetrafluoroethane (the main components of air, which are oxygen and nitrogen, are in fact very rarely used). Hydrocarbons, like butane, were often used in the past, but their flammability forced manufacturers to use fluorocarbons.