Alubond U.S.A Stainless Steel Composite Panel is made of fire rated core, sandwiched between stainless steel sheets in grade 304 or 316 in thickness 0.3 mm. For exterior usage, top and bottom coils are both in stainlesssteel. For interior applications, economical options of aluminum, Aluzinc, Galvanized Steel as bottom skin in combination of stainless steel on the top is available.