Product review (4 stars): These pipes are clean!!!!!
Was having issues with the dryer not getting the job done after moving into a new place. The duct wasn't blocked, but there was about a 1/4" thick layer of lint on the inside of the duct. Never knew about these before, so I tried it with my corded drill with light torque applied. Reduced dry time by about 50%, so the money saved will pay for the product in no time. My only issue is that if you reverse the drill you run the risk of disengaging one the couplings and leaving parts in the duct. It would be nice to see a back up for retrieving the stuck pieces in that event, or a different connection method. (shear pin, key, spline, D flat/set screw) If your mechanically inclined you have no cause for concern.