Double wall smoke pipe is composed of an inner wall of stainless steel, 1/2″ air space, and an outer shell of steel. This product reduces most clearances down to 6″ on a vertical application and 8″ on a horizontal application. Its very beneficial not only from a safety perspective but also a performance enhancer on high efficiency wood stoves. You can only install this product from the stove to the wall or ceiling and never through or concealed within a wall or ceiling. We supply & install these components.