Thermal shock-resistant trays are guaranteed not to break easily. Long service life, porous, and lightweight. Won't fracture in the furnace or during cooling. Bottom channels provide instant heating and cooling. Fire cases of any size and shape directly on it. Porcelain and molten metal won’t stick to tray. Holes can be drilled into trays with a fine bur to create custom supports. Round trays conform to most modern furnace designs.