Product review (5 stars): Rat Approved!
Great  rat tunnel!  I have a buck who has pretty bad eyesight that does not like climbing (leap of faith anyone? No? Me either - I'm with the rat) so I wanted to set up a way for him to get out and about that wasn't a stressor.
He, and my outgoing Tarzan/Stunt Master rat, took to it well.

Side note:  the clips that come with it work nicely for attaching to a cage although I bent the wire over itself and ran it through a cage wire to keep it from migrating. I then tucked it under the tube wall so there were no sharp ends. The tube comes off easily for cleaning and although mine have only nibbled at it once (the 'hey, is this edible?' nibble) I would not use it inside the cage.

UPDATE: I tried this inside the cage since I upgraded both the cage and their play area and even my two new PEW rats, who are heavy chewers, only gave it a few nibbles. A major hit with the rats and I'd say a must have!