Product review (1 stars): Terrible Product Questionable Company
Anyone thinking this is a great product be careful. That opinion will change when the rod breaks and you have to not only clean the vent from dust but also fish the brush out of the vent.
Ten minutes into the job and while pushing the brush by hand two rod lengths into the dryer vent (no drill even brought out yet - just by hand) the rod snapped (clean right angle perpendicular breaks 4 inches apart) in not one but two places within 8 inches of the brush. I was just running it up the vent pipe by hand.  Then I spent the next two hours fishing the brush out of the vent pipe.
The manufacturers web site is deliberately infecting site visitors. Even the major search engines have a warning against visiting the site. Thank goodness I have excellent virus and spyware protection.