Product review (4 stars): Good Product
Worked really well.  I had to clean from both sides to reach the full length of my duct.  It made a 90 degree turn without problems.  The only reason I didn't give it five stars is that they could improve the product by adding locks for the other threads.  It has a lock for the brush thread but not the rod threads.  You have to be REALLY careful not to run your drill in reverse or you'll be trying to figure out how to extract it from your duct.

It also cleaned the flexible aluminum hookup tube fine by spinning the rod and brush by hand.  I held one end of the tube over the AC condenser fan outside to blow out the lint while brushing the other way.

Overall very pleased and well worth the money.