McGill AirFlow Corporation's (Groveport, OH) SilverGuard antimicrobial ductwork is designed to control the spread and growth of many types of bacteria, mold, mildew, and fungus, according to the manufacturer. SilverGuard is available in all of the company's duct and fitting types and constructions, including round, flat oval, and rectangular, single-wall, single-wall lined, and double-wall lined duct and fittings.