Product review (3 stars): Good concept but not ideal execution.
Good concept but the magnetic hold is just not strong enough.
I got this and could not use it on the first two dryers I installed because the exhaust piping into the wall and from the dryer were not close enough - just a few inches higher and lower and it doesn't hold well - was surprised it was so fussy.  Really only works when they line up fairly well.  I did finally get a use for it but I don't think I'll be ordering more of these.  The short telescoping vents work a bit better.