Kair Ducting Adaptor Reducer 204mm x 60mm to 110mm x 54mm Allows quick installation of system 204mm x 60mm airbricks. Part: DUCVKC704 Airbrick Grille or DUCVKC714 Airbrick Grille with Surround. Kair Ducting Converter can be used to convert between Kair 110mm x 54mm Rectangular Ducting and Kair 204mm x 60mm Ducting Pipe Part: DUCVKC5604. It is recommended that you adapt up from 100mm to 204mm, and not the other way round. Adapting down from larger to smaller could create unwanted duct sound and possible fan damage.