Durable, Retardant,nice finishing 1).Durable, in general use of normal life situatioins as long as 50 years. 2).Retardant, low smoke and low gas,high resistance to impact force, acide and so on. 3).High oxygen value, good combustion resistance, self extinguished. 4).Smooth surface, light insulating medium, environmental and beautiful. 5).Sizes,outlooking color, thickness of the tube is optional.