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. Co-extruded with SILICORE® ULF lining for longer cable pulls and higher speed jetting. Available in multiple colors and wall ratios; configurable lengths and options (pull tape, pre-installed cable, stripes). (Source: Chapman Electric product page and Dura-Line TDS listings.)