AAON, Inc. is engaged in the engineering, manufacturing, marketing, and sale of air conditioning and heating equipment consisting of standard, semi-custom, and custom rooftop units, chillers, packaged outdoor mechanical rooms, air handling units, makeup air units, energy recovery units, condensing units, geothermal/water-source heat pumps, and coils. The Company's products serve the commercial and industrial new construction and replacement markets within the heating, ventilation, and air conditioning (HVAC) equipment industry. Its rooftop and condensing unit markets consist of units installed on commercial or industrial structures of generally less than ten stories in height. The replacement market consists of products installed to replace existing components that are worn or damaged. Its primary finished products consist of a single unit system containing heating and cooling in a self-contained cabinet.