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. Duraline Smooth Wall HDPE Innerduct Conduit: Flexible HDPE, co-extruded with SILICORE® ULF lining for longer cable pulls and higher speed jetting; continuous lengths/long reels reduce cost from joins; suitable for direct burial, direct bore, HDD, aerial, trench, tray, plow installations.