"Tie Down" Runners for Drawer System

Hi folks:

My "Red Desert" drawer system has a nice set of aluminium runners/tracks on the top into which I slide some "gizmos" which lock in place, and then allow me to tie down anything that I have on top of the drawers. Found these extremely useful.

Can anyone advise me where I might be able to buy some more of the runners and slide in "gizmos", as I am reconfiguring the top of the drawer slightly for a forthcoming trip.

I do not want to remove the runners from the original drawer top as I am concerned that they may not be as solid a fit once I have replaced them after my trip.

Thanks in advance.
Jack