Product review (5 stars): Amazing! Pair with a shopvac for no mess!
When I bought my new house the dryer duct only had about half the diameter due to years of lint build up.  This thing worked amazing! I paired it with a shopvac at the opening of the duct to collect all the dust/lint.  I had no mess to clean up and wasn't breathing all that dust. In about 30 minutes, I was able to use my dryer!