D3539 Flush Steel Door Door Type 1 Lock Type Mortise Material 16-Gauge Thermal Insulation U-Factor 0.41 Door Opening Height 84 in Door Opening Width 48 in Thickness 1-3/4 in Agency Compliance UL 1 1/2 Hour Fire Rating 6-5/8 in 39-5/8 in 72-5/8 in 38-7/16 in