Product review (5 stars): Great product. It gets a little screwy if you ...
Great product.  It gets a little screwy if you try to use all twelve feet at once.  I suggest you connect two rods, insert these into the dryer vent, then add additional rods as needed.  I purchased 2 sets because my dryer vent is just a little over 12 feet and I wanted to make sure I cleaned out the entire vent.  WORKS GREAT.  HEARTILY RECOMMEND!