Product review (5 stars): Worked great. I was amazed at how much gunk I ...
Worked great.  I was amazed at how much gunk I got out of there.  Note:  When they say only turn it clockwise they mean it.  If you turn it the wrong way you could have the head come off in the duct.  This didn't happen to me but it's fairly obvious right away why they tell you to do it that way.