Product review (5 stars): Must have this if you have a dryer vent on your roof
Everyone who owns and uses a dryer with an exhaust tube should consider having one of these. If you can't reach all the way into the dryer exhaust tube its likely that lint will accumulate there and eventually reduce the airflow and efficiency of the dryer.

My dryer exhaust is through the wall and out a vent on the top of a roof (vent is about 16 feet away from the entrance into the wall). I needed an extra set of connecting rods. My dryer run time increased slowly to more than four times as long, however after one cleaning that took about 10 minutes it was back to under 30 minutes. I used a regular drill to spin the brush.

I would recommend the product.