Product review (5 stars): Works as advertised.  Fantastic product.
I paid (and this is cheap) $60 for someone to clean it one year.  It usually costs over $100.
I paid less than that for this kit, extension kit, and lint catcher bag.

My duct is approximately 26 feet long and straight except one right angle.  So i have to clean it more frequently.  I'll be saving a couple hundred dollars every year by using this product.

Manually operating the product did not work because the brush would stop when there was a clog.  But once I hooked it up to my power drill, I didn't have any problems.  Also, I left like the brush was getting caught on a sharp turn if the drill is not operating it.

It turns out the duct was extremely clogged and probably damaged our dryer.  The air flow was non-existent before I used this product.  And afterwards, the air flow is undeniable.