Product review (5 stars): Probably saved my house from a fire!
I have a long horizontal run from my dryer to the outside - roughly 18 feet..., plus an 8 foot vertical run. I turned on the dryer and inserted the brush wand by wand driven by my battery operated drill just as the instructions explained. What I received was a mound of lint that filled a 5 gallons bucket - yes, a five gallon bucket. I don't know how any exhaust was exiting the dryer at all with that much lint present. Wear eye protection and a dust mask while doing this because the lint is blown outside towards you.

The dryer is working fantastic now. Before it took hours to dry clothes. I plan on doing this again in six months to see what the accumulation of lint is. This is probably the most useful item that I've purchased in a long time. It also worked exactly as advertised, including around a 90 degree turn in the vent line. Do yourself a favor and make this tool part of your regular home maintenance!