I ordered it on line and let it sit in the box a little over a week because... There on the box was my very old Q series with a big red circle and a dash through it! Eventually, I yanked the thing out and thought, maybe I can re-sell it if it doesn't work.  What seems like a perfectly easy snap -n-play cart actually required a visit to YOU TUBE.  The cart was remarkably easy to assemble, but the drawings that came made with it weren't that clear.  It did fit my old Q, so I wonder why the red circle with a dash through it?