Product review (5 stars): 23 ft of duct cleaned.
Worked great....had 3 inches of the 4 inch pipe filled with lint in a 23ft run of dryer duct.  Had to buy the extension for this so I could have a total of 24 feet.  Did not need to use a drill to get the job done. The pipes I believer are well built.  If you use a drill put it on a low torch setting. My heating element and thermostat kept going out...so this should fix that from happening for a while.
My only complaint is that the brush should be a little more stiff.
But this got the job done