Product review (5 stars): Amazing Amount of Lint Liberated!
The brush and extension rods are of good quality, and are a bargain (in my opinion) for the price.  I used them in our rather long dryer duct and ended up with the equivalent of a plastic grocery sack of lint that the brush loosened.  I went about the cleaning process backwards, starting at the end.  Should have started at the dryer.  Procedure was to push in the brush and add extension rods until I couldn't push the brush any further.  Then, I attached a small cordless drill to the end of the rod and turned the brush clockwise (make sure, counterclockwise will unthread the rods!) as I pulled the brushes out.  Then, I turned our dryer on air fluff and watched large pieces of lint come blowing out.  I did this three times with large amounts of lint coming out.  I didn't get much out of the dryer and the pipe closest to the dryer.  All my lint seemed to be where the pipe exits the house and then goes under our deck.  I'm thinking the humid air in the duct hits cold air in the winter, the water condenses and then lint sticks to the water.  Bottom line is that this brush works, is capable of cleaning a good length of duct, the extension rods are in handy two foot long segments, and the cleaning kit is a fantastic value, even if you only use it once or twice.