How ComforTrack works: Along with Cellular Shades, 3 levels of defense of ComforTrack Plus System

Sidetracks for shade

ComforTrack sidetracks against the window’s energy gap. It seals off the gap between the shade and window to create a solid insulating barrier.
The Flex Seal is a clear spring seal that is hidden between the cellular shade and the sidetracks. It flexes open and closed when the shade is raised and lowered to help create an energy tight seal.
The final barrier makes a big impact in closing the energy gap. The small space between the head rail and the window frame is sealed off with a foam seal which is discreetly attached to the back of the head rail. - see Comfortex Manufacturer's Certification Statement (PDF)