... the heating wire, and the gap part of the tightly filled in crystallization of magnesium oxide with good thermal conductivity ... in showers, water dispensers, boiling, dishwasher and various types of heating appliances, etc.5)Insulation materials: magnesium oxideTube Material ... ,Φ8.5,Φ8,Φ6.5Length:200mm5000mmSurface treatment: a variety of plated nickel, passivation, black, spray.Electric heating tube ...