Designed for high frequency, severe traffic openings 1-3/4" (44.4 mm) custom construction Seamless design Rated for heavy-duty to maximum duty use 22 gage steel stiffeners spaced 6" apart, welded to face sheets every 5" Fully welded edge seams enhance strength and appearance Fiberglass insulation to limit thermal and sound transmission Inverted end channels welded to both face sheets 7 gage (4.2 mm) steel hinge reinforcement