Nordfab's QFS system consists of three parts: Caulking, Gaskets and O-ringsA sealed duct system is largely dependent on the skill and care of the installer, so Nordfab cannot guarantee a 100% leak free system. However, if users consult the technical data (to ensure that our gasket and sealing materials will stand up to the materials being conveyed) and take care in the installation process, this system has proven that it can be ‘Leak Free'.