The Model 418 door is a high-quality, heavy-duty insulated door that provides protection against heat and cold environments. Fabricated of 16-gauge, flush galvanized steel exterior and 26-gauge steel back cover, these 2″ (51 mm) thick doors offer an R-value of 7.35 (1.29 W/Msq). A wide array of options allow these doors to meet the most stringent project requirements that call for a degree of thermal efficiency.