The thicker AP/Armaflex elastomeric foam insulation is suitable for the extreme temperatures and humidity associated with commercial refrigeration and some cold-water systems. The insulation conforms to National Fire Protection Association Standards 90A and 90B, which means it meets the required 25/50 flame spread and smoke index that is required of materials used in return air plenums and, according to the company, it exceeds requirements for other building applications. The 1-1/2-inch thick insulation is designed to provide protection against mold and mildew growth, due to its smooth surface and low water vapor permeability.