Product review (5 stars): Works Great !
I have a 17ft  4" (3 3/4" actual inside diameter) round metal duct dryer vent that goes into the wall at floor level, up 8ft., makes a 90 degree turn, then goes through the ceiling 9ft and out the side of the house. I got a quote of $199.50 + tax to have it professionally cleaned.  That is insane!  I purchased this plus the four pack 12' extension kit since I was cleaning more than 12'.  I followed the instructions and it worked like a charm.  Easy, no problems, and a clean dryer vent and dryer for about 1/5th the cost. You do need a drill to attach the rods to though I had no trouble pushing it the straight length of the 9' horizontal duct without one.  The 90 degree turn not so much, but it was easily maneuvered by the auger action once I attached it to the drill.  It's nice to buy something that actually works and saves you money.