• Corrugated Innerduct is an HDPE tube with alternating large and small annular rings that allows the innerduct to have a thinner wall yet retain a significant crush strength. Corrugated innerduct also has superior all weather flexibility. Corrugations also eliminate memory making the innerduct easier to handle in tight conditions and eliminates spiraling of the innerduct when pulled into conduit. Lack of memory is the primary reason corrugated duct has significantly less friction than any smoothwall product. Smoothwall innerduct depends on a continuous heavy wall for strength. Ribbed innerduct is smoothwall innerduct with a series of ridges extruded into the inside wall.