If you don't plan on putting huge items in the back that often, it is worth it to get the Nissan pet protector.
a) As Schlud said, there is ample room underneath the cage if you fold the seats down, and if you need to put sofa or a desk in the back, then it is only a few screws to take it out.
b) I have never, NEVER, seen a "generic" cage that didn't start to rattle, scratch up the interior, and become more of a head-ache than it is worth.
IMO, one item that is well worth the premium charged for it because it is an excellent fit and excellent quality. Combine it with the Nissan cargo protector and my two wet, muddy, crazy labs have not yet been able to ruin anything.
TimR
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