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. Product is co-extruded with SILICOREAE ULF lining for reduced friction and longer cable pulls. Available in continuous lengths/reels (1000 ft reel typical) and in a variety of colors and stripe options; used for direct burial, bore/HDD, plow, trench, aerial, and tray installations.