Product review (5 stars): Dryer pipe with a 7 ft vertical elevation over 9 foot length - works like a champ
My dryer setup sucks:  4" rigid pipe goes UP to the exterior (7 ft vertical elevation over a 9 foot length).  Dryer just quit working b/c the thermostat said "No fire for you!".  I had already bought this kit (2014) b/c I *knew* I had a guaranteed problem despite being a fanatical cleaner of the dryer screen (open dryer? I clean the screen).

Used all four extensions w/o a drill (I was a lazy girl - hand twirled clockwise).  Recommend using duct tape over the connections per instructions. I did not do the "super" cleaning b/c of my setup (horizontal duct directly from the laundry room to garage is permanent as yesterday's laundry rooms are much narrower. The upward slope is from garage to outside).  But even when twirling by hand, the amount of lint removed was amazing.

Husband says the connections are "well machined".  BTW, after looking at the pics online, I think I want to do it properly w/ a shop vac (I hate lint).