The Base Closure System provides not only strength but ultimate protection against the weather. The heavy duty tall 14 gauge base angle on the interior prevents dents, creasing and serves as a kick plate in aggressive work environments. The Base Trim is supplemented with a preformed foam closure to keep out rodents and insects. Only Ironbuilt supplies base closures as a standard; the other companies provide no base closures and use a small, flimsy, one piece, light gauge base trim/angle with no closures. Custom special base trimmed sealing closures will be required for flush concrete conditions or aprons please advise your dealer or representative.