All the Kury footwear are all SAE from my experience. The grip end caps are 4-40 SAE. I've lost some thread in one hole of mine and retapped to 6-32 SAE w/o any issue with fit.
I believe this is correct. Way back at startup, Kury principally catered to Harley (and a US market) so most things are SAE.
Seems to me you can google Kury parts/install descriptions/lists (maybe PDFs) and they should have screw/bolt sizes. Or call them.