Donaldson Company, Inc. is a vertically integrated filtration company engaged in the production and marketing of air filters used in a variety of industry sectors, including commercial/industrial (engines, exhausts, transmissions, vents in private vehicles, hydraulics), aerospace (helicopters, planes), chemical, alternative energy (windmills) and pharmaceuticals. Also the company's research division, located in Minneapolis, Minn., participated in defense-related projects for various military applications.