Rockwool tubes are used for insulating flue liner reducing any condensation in the flue pipe and are commonly used in large open chimneys or when the chimney is situated in an open aspect. The tubes are manufactured from non-combustible Rockwool. The use of these tubes significantly reduces any occurrence of penetration by vermin, the growth of mould, bacteria or fungi. We recommended that all joints are sealed using 50mm wide aluminium tape (sold separately). The Rockwool Tubes are rated to withstand hot temperatures up to 500 degrees.