Still trying to decide between the mats that fold up and the ones that don't. Space wise five stacked flat and five folded and stored will take up about the same amount of space so that isn't really a good guideline. I am concerned about three things with the fold up ones - does the child's hip or whatever ever end up in the fold part and not properly supported by the mat depending on their size, do the kids ever fold them up when they should be resting - think what babies do with the boards in the packnplays, and third, does the constant folding wear them out sooner so they rip. Forget now if it was Wintergreen or Allaboutkids but I saw a fold up one that was four sections instead of three that looked interesting and the price was better.