Product review (5 stars): Its great. Just DONT RUN YOUR DRILL IN REVERSE
Its great. Just DONT RUN YOUR DRILL IN REVERSE! As long as you remember that, you'll have clean ducts in no time with almost no effort. Its a great too. Put some tape over the reverse on your drill or something. I didn't and when I hit reverse on a drill I don't use much. I got to spend an hour fishing it out of the duct backwards. But as long as you forward you'll be fine.