Product review (5 stars): Clean your vents !
Really great product.  The rods are solid but really flexible. Works best in a drill.  Use only clockwise direction on your drill or it will unscrew the sections.  I have a really long run of pipe over 15 feet.  I used inside and then outside.  Unreal how much stuff gets stuck in there.  Do yourself a favor and clean your dryer vent.  Clothes dries a lot faster now.  Great product.