Product review (5 stars): Using the drill in reverse can easily cause the rods to unscrew while inside your duct
When my dryer gave me the "clean filter" alert, I suspected the dryer ducts in my new house were plugged up, because I clean the filter on the dryer after every load. I was worried this brush might be a little too tough and accidently poke holes in the dryer duct, but that was not a problem. It's exactly as stiff as it needs to be. The white poles included are flexible. USE THE DRILL CLOCKWISE ONLY. Using the drill in reverse can easily cause the rods to unscrew while inside your duct.  They screw together easily BUT the instructions say you're suppose to tape them together once connected. How ghetto is that?? Just design it better. Maybe a push lock and latch system or something. I also thought it was a little strange they just want you to jam the metal threaded end of the pole into your drill chuck and clamp down on it. I was worried it would crush/ruin it over time. But the metal is very solid and the drill chuck left no marks. Attached are two pictures of the lint I pulled from about 8 foot of duct. The second picture shows what loose stuff blew out once I turned the dryer on.