Babcock-Davis B-RHA Roof Hatch 48 x 48, Aluminum The Babcock-Davis B-RHA roof hatch is manufactured from aluminum to ensure years of dependable use, even in most extreme weather conditions. The lids are mounted on a 12" curb with cap flashing to ens ure against leakage. B-D roof hatches come standard with compression springs, zinc plated steel hardware, and insulation in the cover and at the curb perimeter. Babcock-Davis B-RHA Roof Hatch 48 x 48, Aluminum Features: • Cover & Liner: 11-gauge (0.090") aluminum cover with an 18-gauge aluminum liner • Curb: 11-gauge (0.090") aluminum, Optional: 11-gauge double wall curb (curb liner at exterior) • Hinge: Tamper-proof hinge contained within hatch as part of a spring assembly • La tch: Turn handle • Spring: Greased compression springs enclosed in telescopic tubes, which counterbalance the door to require no more than 10 pounds of opening force • Hardware: Zinc coated steel, Optional: Stainless steel • Insulation: 1 " thick rigid fiberglass in cover and 1" at curb perimeter • Mounting Flange: 3½" on a single wall curb, 2½" on double wall curb. • Finish: Mil