In a Corrugated Pip, the Upper Layer Is Corrugated Polyethylene, Which Has Low Pressure, Which Makes Its Protiation of the Inner Layer of the Pipe. The Inner Layer, In Turn, Consists, On the Contry, of High Pressure Polyethylene. HIS DISTINGUSHED DIFFARENCE IS that he is Absolutly Smooth. It is with Such Such Smoothness in Order to Make The Laying Much More Convenent, and Also Surface Allows The Cable Not to Rub ON IT IT and Not FAIL BEFORE THE DUE Time.