Product review (5 stars): A must have for everyone whose dryer vents through the roof
My dryer vents up in the attic to the top of the roof... I bought this since my dryer was taking too long to dry.  After using this I got a grocery bag full of lent out of the ductwork. Amazing. I used this inside the house working my way through the roof both maually and with a power tool.  I still need to get on top the roof and use this.

Tip:

Go up and down not just up - you will get more lint out that way.  And make a few passes with this especially if you have never used this before.