Made with two layers of steel and polyurethane foam insulation, Models 8300 and 8500 are extremely durable. Not only that, they are offered in four designs with factory-finished colors or an optional bi-directional wood grain finish that emulates the beauty of real wood. Models 8300 and 8500 come with foamed-in-place polyurethane insulation with an R-value* of 12.12 for Model 8300 and R-value of 16.22 for Model 8500.