Hollow metal doors are designed to meet architectural requirements for full flush doors. They combine the strength and dimensional stability of steel with structural integrity. The continuous bonding of core to metal provides an attractive, absolutely flat door, free of face welding marks. Tests have proven hollow metal doors are highly resistance to impact damage and offer low thermal conductivity. Lite kits and glazing are available in standard and custom configurations with fire ratings up to 3 hours. Flush frames are available in 18, 16, 14, and 12 gauge cold-rolled or galvannealed steel and also in 16 or 14 gauge stainless steel. Frames can be knocked down or welded at the miters and ground smooth. The 12 gauge frames are saw miter welded or butt end welded corner construction only. They are available for either 1-3/8” (35mm) or 1-3/4” (44mm) thick doors. Hollow metal frames are manufactured for all wall conditions such as masonry, steel stud, wood stud, and poured concrete.