Product review (3 stars): Works good....if you only have one turn to go around
It has no problem going around one turn, but if you have more than that it's not going to make it.  As soon as it got to the second turn it wouldn't go any further and the rod twisted off.  Luckily I was able to retrieve it.  I was able to take the brush off and rig up a better tool by modifying it and was able to get it to work.  Just be cautious if you have more than one turn in your duct.