The 640 and 641 Series doors are ideal for openings requiring a counter-type fire-rated door. Common applications include factories, schools, concessions, hospitals, cafeterias and retail settings. Labeled with either a 3-hour Class A rating for masonry applications, or a 1-1/2-hour Class B label in non-masonry fire walls, these doors are designed to expand upward in a fire, allowing the guides to be installed flush with the sill. Their compact, box-like form also provides an attractive finished appearance that requires minimum sideroom. The 640 Series has exposed components made of primed galvanized steel while the 641 Series exposed components are of stainless steel.