Product review (5 stars): Excellent Product!!
OMG!!  Awesome product!!  I have a long dryer duct (about 25') with additional booster fan installed (by Fantech-another great product).  My run has 3 90 degree turns as well.  The length and 90s makes my system especially susceptible to clogging and reduced performance of my dryer.  I just used this product to clean out the runs and it works so well, the insides look almost new, seriously.  The shop-vac attachment makes connecting my vacuum to one end a breeze.

Cannot recommend more, excellent product, worth every penny.