It's a long story, but these KM clasps are attributed to Juncker, not Klein, as the manufacturing characteristics match the "non-Klein" one-piece Heer clasps (which forensically shares some pin characteristics with the Juncker EK1 clasps) and also the Luftwaffe one-piece clasps for which Juncker-labelled packaging exists.
Not surprising given Juncker's status for higher end orders.
They're Tombak. Material restrictions in late wartime didn't apply to the higher orders (hence no zinc German Crosses)
There's only one manufacturer of the KM clasp known, but two variations based upon the trimming characteristics. The "earlier" one, "Type 1" as alluded to by Hubert in an earlier post, has variable hand-cut internal cutouts whereas the "Type 2" (same die characteristics) used a standardized trimming die for the internal cutouts.
Best regards,
---Norm