A specialized form of charcoal, this final filtering agent removes tastes and odors from the air. It absorbs oil and water vapor, chlorine, nitrous oxide, and small amounts of carbon monoxide and dioxide. NOTE: Activated carbon should be the final chemical in the filtration train and must always be preceded by the desiccants. When damp, the effectiveness of charcoal is reduced and may even release previously absorbed contaminants. Also, wet activated carbon of even high quality may form small amounts of sulfuric acid which in time can do serious internal damage to a filter housing! Packaged in a 1 gallon, 3.75 lb bottle.