The Grieve Corp. (Round Lake, Ill., U.S.A.) offers its No. 921 electrically heated, heavy-duty box furnace, designed for various types of heat treatments at temperatures as high as 1093°C/2000°F. The furnace interior measures 610 mm wide by 1,220 mm deep by 610 mm high (24 inches by 48 inches by 24 inches), and features 178-mm/7-inch thick, ceramic-fiber-insulated walls and a 114-mm/4.5-inch thick firebrick-insulated floor. Its motorized vertical-lift door contains an in-door heating element, for improved heat uniformity. Other features include a digital programming temperature controller and a manual-reset excess temperature controller with separate contactors, for improved safety.