Wheeled case space saver

I have a wheeled laptop case and needed a way to tidily store some small equipment (battery packs etc). I noticed that there was some wasted space between the handle storage pillars at the rear of the case which would easily accommodate the equipment but no way to hold it in place.

So, this device clips between the two pillars to provide a neat and simple way of storing small items in there. I imagine it could be scaled easily enough to fit different cases.

There are two different items: one which has a "shelf" to stop the items dropping and the other which doesn't. This gives some flexibility in height.