Product review (5 stars): My vents were gross
Our dryer had stopped drying, even after multiple cycles. I ordered this to clean out our ducting and was able to clear out a clog, after that lint started just pouring out.

The directions were very clear, make sure to duct tape the joints together.

The poles are very flexible but sturdy and they were sufficiently long to do the job. I found that the brush got deeper into the pipe if it was spinning as I fed it.

After we got done my exterior vent is definitely blowing with more force, and the dryer is running much better.

Here's a picture of what came out, there was a pile inside the house as well.

10/10 would recommend.
13/10 with rice.