Every Invisco system comes with dampers designed to fit right over your room’s ceiling to stop all air from coming down when the fan is off. This is the most effective way to block cold air automatically in the winter.
In some climates the attic gets so cold that even with this damper at the ceiling, it could get real cold and start chilling the air below it. If that happens it could cool your room in the winter.
To prevent that Invisco engineers invented the best high rating dual insulated dampers in the industry. Called the R60 damper, it is a patent pending assembly described in more detail here.
Below is a picture of a typical gravity damper. These are very cost effective and do the same job as motorized dampers that cost twice as much or more.