Zalman Z11 standoff size

I have this Zalman Z11 laying around and it'd be a shame not to use it. The issue is it only has 4 preinstalled standoffs. I can't find the others, and I'm curious as to the size if the standoffs I need. I think it may be C40 but I'm not sure.

That case... no. It would be more of a shame to put some poor working components in that thing :(

It's all I have right now. I plan to pick up an R5 or H630 eventually.

That case is just a trigger for me lol. I used to have one and I absolutely hated it.

Do you know where I can get standoffs for it?