The Duraline HDPE Conduit, 4 in, Schedule 80, Smooth Wall, Black (vendor part 2034028610, Millennium part 522709), gives crews a heavy-wall duct option for fiber or utility runs where added crush resistance matters, such as roadway bores or high-traffic trenching. The smooth interior keeps friction low during cable placement despite the thicker Schedule 80 wall. Black HDPE construction stands up to UV exposure during staging before burial. Stock it with matching couplers and duct plugs to complete 4-inch Schedule 80 conduit runs.