Enjoy having complete electronic control of which rooms your HVAC system heats or cools with this 24V Motorized Duct Dampers that can be automated (or manually controlled) in a variety of ways. These motorized dampers can be configured to open and close partially or completely depending on your application. These units are compatible with our popular RCS HVAC Zone Controllers (see our 24V Electronic Duct Dampers for other compatible units). 24V Hardwired power supply included. These models offer the flexibility of being controlled with any mechanical thermostat, an appliance module (when used with a plug-in 24V AC power supply), or an X10 Universal Module (all sold separately). With electronic duct dampers, an appliance module and any X10 timer, you can reduce your heating/cooling expenses by cutting off airflow to unoccupied rooms during work hours. Or, if you want a room to be a little colder or warmer than the rest of the rooms in the house (i.e. grandma and grandpa's bedroom), any mechanical thermostat can close the damper when a pre-specified temperature is reached. The 24V Motorized Dampers are available for 6", 8", 10" and 12" duct diameters, and can be ordered in normally-open or normally-closed configurations. When no power is supplied to the Normally Closed unit, the damper will be closed. When no power is supplied to the Normally Open unit, the damper will be open.