Well. It arrived today. My vent run is vertical from laundry room to roof with one 45 degree turn. I used it with a cordless drill and ran it up through the top. I could tell it was at the top because it was getting stuck at the roof cap exit. About a plastic shopping bag full of lint came falling down as I brought the brush back down toward me, and this is AFTER using an electric leaf blower about 3 months ago.......I then got a ladder and went out to the roof cap and used an extension wand with a dryer lint brush attached to the edge (never actually getting on the roof itself) and then brushed away what lint was stuck on the roof cap....Then I got the leaf blower (just for good measure) to see if any additional lint would come out of the vent..OH MY GOD>>>>My roof was COVERED with lint!
At this point I'm paranoid..So I do it all over again, this time I got no lint out at all. I can't believe how easy it was.....The hardest part of it all was pulling the dryer out and re attaching the duct to the vent.......Total time of about 40 min's...I can't believe that much lint was able to stay in that run even with me using an electric leaf blow twice a year since I've moved into this house.....I guess the leaf blower wasn't really working as well as I thought it was.