Product review (3 stars): Worked pretty well
I think this worked as it was supposed to, I've never used one before.  My only "con" is that I had to cut the flex hose, b/c the lip on the end didn't seem to allow it to go all the way down the narrow cavity in my dryer vent.  Mine is on the inside bottom, just inside the door, it's not up on the top of the dryer.