This flexible aluminum foil-faced ceramic fiber blanket wraps around and insulates the liner. It helps the liner warm up quickly to establish strong draft, reduce the heat transfer to the outside of the chimney and reduce condensation. A double layer of the 1/4″ thick 8lb. density blanket is required for applications where combustible materials are less than the code specified clearances from the chimney (usually 2″). The foil listing allows combustible materials to be in direct contact with the masonry chimney when installed in this fashion. Tape seams with foil tape , then slide wire mesh over insulated liner; stretch mesh and clamp at top and bottom with clamps.