Product review (5 stars): Best money I've spent!
I don't do many reviews but I had to for this product! Boy does this work!!!  Be sure to read the directions, did I say read the directions yes I did?! So many issues come from not reading them. Be sure to never have the drill in the reverse direction (counter clock wise) when using this product. It is very easy to use the only thing that takes time is screwing the sections together and duct taping them for additional protection from losing a shaft piece down the duct work (because the drill was reversed and unscrewed a section of rod). I have a 13 foot run of duct and from everything I can tell it did a great job cleaning it. The newer clothes dryers cleaning out the lint trap in the dryer doesn't cut it stuff still gets by. I found after 18 years and with our new 1 year old dryer it pumps out the air and does blow a lot through the lint trap even though we clean it every time we use the dryer!
  The other thing I can think of saying is take your time cleaning it will pay off and whatever you do don't sit with the rod in one spot long just in case the rod is sitting on some sharp edge which could cut it and again you lose the rod down the vent shaft.