I see that there are currently several makers of guide rail squares (*edited) that use the same latch as TSO.
Is is possible to source them? I must have looked at more than 10.000 latches on google by now...
I know I found these exact same latches there a few years ago. I needed some to replace some broken ones at work. It's been a few years and I don't remember the name of the manufacturer but they are online and you can buy direct. But prices were close to McMaster so there wouldn't have been much savings.
I bought a few of this type of latches few years back. Looked just like the one TSO uses except for the vinyl on the latch. I can't find supplier info on it but google "draw latch".