Product review (5 stars): Works well
The tool works really well.  We were thinking about replacing the dryer until we used this tool to clean the vent and discovered our dryer was able to get the job done like a new unit.
Since the vents are problematic based on their length, it seems like a waste of time to make the extension a separate purchase.  Recommend the manufacturer include the extension as part of a single purchase with the main unit.