The Wide Loft Loop is a great solution for giving your guinea pigs the awesome ability to do unrestricted, full-tilt zoomies in their Large, XL, or Jumbo cage (this item does not fit on Small or Medium cages unless it's offset).
We highly recommend wide lofts be OFFSET by one grid (not pictured), which adds approximately 15" to the overall cage length. Access to the far corner underneath the loft is limited for cleaning and retrieving your guinea pigs unless you offset it as adult arms can't reach that far.
Please see this article for more info about HOW to offset (there are two different styles) and how offsetting changes the COVER needed.