Product review (5 stars): Easy to use.
Used with my drill attached and had the dryer vent cleared out in minutes.  In fairness I did not try the manual crank. So I can not comment. Works as advertised though. I bought because my dryer duct was longer than 12 ft. And that is the max for anything at lowes or home depot. It came faster than I expected. And I used one of the smaller heads to break up the clogs. Then I put the 4 inch back on to clean out the last of the lint. Worked like a charm.