The chimneys inner liner is made from 304-alloy stainless steel. The outer wall is 430 series alloy stainless steel. The mineral wool insulation is formulated for optimum performance while dramatically reducing chemically active ingredients. It provides a thermal delay that resists and contains surges of heat keeping the outer liner cooler. SuperVent couplers are embossed which reduces moisture penetration increasing longevity of the chimney. Measures 7in x 6in.