Whole house humidifier, manufactured by Trion Corp. The Model G300 Bypass Humidifier was designed with ease of service in mind. Installed on the warm air plenum or return duct of a forced air furnace. This model constantly flushes away trouble causing minerals not deposited on the replaceable humidifier filter and provides exactly the right amount of moisture in vapor form. Has 6 bypass duct collar that is switchable to either side.