Dura-Line Smooth Wall HDPE Innerduct Conduit All Dura-Line's smooth wall conduit meets or exceeds one or more of the following standards: ASTM F-2160, ASTM D-3035, ASTM D-2239, ASTM D-3485, NEMA TC-7, UL 651, UL 1990, Bellcore GR-356. Features: Can be used both as outer conduit or as innerduct. Flexible HDPE makes gradual bends without using special tools or equipment. Co-extruded with SILICORE® ULF lining for longer cable pulls and higher speed jetting. Continuous lengths/long reels reduce cost from joins. Can be installed in cold climates. Installation Methods: Direct burial, Direct bore, HDD (horizontal directional drilling), Aerial, Trench, Tray, Plow. Applications: Telecommunications, Electrical, Industrial, Municipal, Wind farm operations, Other underground applications.