Product review (5 stars): Worked like a charm
When we had our second floor master bedroom and upstairs laundry room added to our home, built mostly over our garage, the contractor used a flexible type dryer vent hose and ran it between the new floor and the ceiling of the existing garage.  It's approx. 20 ft. long, mostly a straight run but with a curve to come up thru the laundry room floor to connect to the dryer.  It vents to the outside on a side wall over the garage.  I was very concerned about trying to use this cleaning system to clean out that length of hose and in an area that, if it failed in anyway, would require either pulling up a part of the floor or pulling down a part of the ceiling in the garage in order to remove the brush.  To clean this length of vent hose, I decided to start from the outside and finish from the inside.  I took off the vent outlet and disconnected the hose from the dryer.  Hooked up my shop vac at the dryer end using the adapter supplied and then started running the brush in from the outside using my cordless drill.  I followed the instructions to the letter when connecting rod sections, taping the joints securely with black electric tape.  It worked perfectly!  There were places that I could tell that the hose wasn't exactly straight and the rotating brush just cruised along without any binding or slowing down.  I ran the full length of rods back and forth several times to free up as much of the lint as possible.  Then I switched to the inside, again using the adapter, I first inserted the brush with one rod connected, thru the adapter and into the vent.  Then I secured the adapter again to the vent hose using the hose clamp from the dryer so that I was vacuuming and brushing from the same end.  This is the end that also had the sharper bent where the hose went into the floor turning 90 deg. under the floor.  Again it worked perfectly, navigating the curve(s) with ease.  I had to clean the vac filter canister several times to keep it from clogging too much and I was very careful not to reverse the drill.  This system saved me money big time as a vent cleaning of this type in our area would be at least $100 each time.