Insulation | Extruded insulation with 3 non-separable layers: Inner layer shall be solid PP skin with minimum average thickness 1 mils, minimum thickness at any point 0.9 mils, middle layer shall be fomed PP with minimum average thickness 4 mils, minimum thickness at any point 3 mils and the outer layer shall be solid PP skin with minimum average tickness 1 mil, minimum thickness at any point 0.9 mils. |