The CB Universal Wall Bushing consists of two parts - an inner and an outer part. Simply insert the wall bushing into the stowed shaft. Due to the exact fit of the two parts, the wall bushing can be simply pushed into each other and thus adapts to any wall thickness. It is no longer necessary to precisely stamp, plaster or trowel the wall. The assembly time is extremely shortened. The wall duct replaces the ventilation grille installation frame. Simply push the grille into the wall duct. The wall duct is made of galvanized steel and can be painted black if required by the stove setter on the construction site. The insulation area can also be covered by the wall feed-through.