Product review (5 stars): Works great!
After years of having to hire a chimney sweep to clean out our extremely long dryer vent, I found this product.  We have used it a couple of times already (with the extension kit) and have found it to work really well.  You do need to use an electric drill rather than a battery operated one because it needs more torque to clean out the vents.  Our dryer vent is 21 feet long and has a 90 degree bend in it and we're still able to clean it out with this product.  The dryer runs much better now that we can keep the vent clear.