Aprilaire is the bran under which Research Products Corporation markets indoor air quality products with the two names being largely synonymous. Research Proucts is based in Madison, Wisconsin, United States and manufactures humidifiers, dehumidifiers, air cleaners, thermostats, ventilation and zone control HVAC systems. The first Aprilaire branded product was a humidifier introduced in 1954; this was the first evaporative whole-home, flow-through design humidifier to be marketed in the United States.