Flo Thru Super-Dutyï¾™ Coated Element Heavier materials throughout, heavy SS 316 Duraseal bulkhead fittings, incoloy 800 sheath, ET-117 Dupont Teflon filled coating for extreme resistance to chemical attack, temperature, scaling , corrosion, and mineral build up. Duraseal bulkheads are epoxy potted with hi-temp epoxy. Individually boxed