Monitor arm for L5

Does anybody know what kind of mounting rail is used on the L5? I am looking to find 2 monitor arms to mount on the built in rail, but cannot find one. I thought it was similar enough to a T Mount to try that but the pieces they supplied to make it fit a T mount were too small. Thanks

It was a custom creation by Jands. I did have success machining a couple of Unistrut nuts down and bolting them in but it was quite a bit of work. In the end it may be easier to use an off the shelf monitor arm either bolted to the desk or the case tray.