Olympus PEN housing - port O ring size?

[InTheHighlands]

I wonder if anyone happens to know the O ring size for the ports on the AOI/Olympus housings for the PEN series of cameras?  By measurement, appears to be 76mmID x 3.0mm cross section - but I wonder if AOI/Olympus would use standard metric O rings, or JIS standard?  Closest JIS standard would be 74.4mm x 3.1mm.

 

Answers and thoughts appreciated! 

[AlClarence]

AOI list them as 74.4mm X 3.1mm here https://www.aoi-uw.com/aoi-por-02.html

 

[InTheHighlands]

Excellent, many thanks - although this means I've ordered the wrong size........!  And, I'm pretty sure, the ones supplied with my AOI / Zen ports are not silicone........