Product review (5 stars): Do this before you install a dryer vent fan!!
I used this system to clean my dryer vent before installing a booster fan.  This system worked great!  I removed over 5 gallons of lint from about 30' of pipe.  Read the instructions or view the DVD before you use the system.  I found the instructions helpful, especially the tips for adding and removing rods.  My dryer performance improved dramatically with the cleaning.  After I cleaned the vent pipe I installed a Tjernlund Dryer Duct Booster, Model #LB-1.  The fan improved my drying times a bit more; but, more importantly, it increased the velocity of the air in the pipes so that the lint would not settle out again.