Looks like JIS for big Chinese stores. On my calipers, the outer diameter of the cup insert was 30.08mm. It comes with a star nut. On a 2002 LeMond steel frame (Reynolds 853) I had to slightly gouge the inside of the head tube to ensure the use of a pressing tool. because it could be pulled out by hand without gouging. It worked for me, but I would prefer common standards to avoid surprises.
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