General 900M is a whole-house humidifier that can be mounted on a warm air or return air plenum. It features a flow-through bypass design that allows for continuous operation without the need for a humidistat. The humidifier is self-retaining and includes a saddle valve for easy installation. It has a 6" outlet that can be mounted to the right or left of the unit, and it can be used with either hot or cold water. The humidifier has a built-in air pressure switch that turns the unit on and off as needed, and it has a 24V transformer for safe operation.