Attributes . Element assemblies shall consist of three steel sheathed heating tubes in a furnace-brazed, plate-finned, block design. Each sheathed tube shall contain coiled Ni-Chrome wire embedded in an insulator of Magnesium Oxide. The element assembly shall provide up to seven (7) possible wattage configurations for selection during field installation. The use of external resistors, diodes, or other weak links to obtain multiple wattages will not be acceptable. . Names