Sheath material is 304 Stainless Steel which provides high temperature strength, good thermal conductivity and resistance to oxidation. Sheath is roll crimped over a 304 Stainless Steel end disc. This style end seal is not moisture proof. Helically wound Nickel-Chrome resistance wire is evenly stretched and strung through ceramic insulators High purity Magnesium Oxide (MgO) is used to fill all remaining space inside the ceramic insulator. The standard termination for Low-Density Cartridge Heaters is Type F, consisting of 10" (254 mm) internally connected flexible lead wires.