OTK master fill plug thread size?

I just wanted to confirm that the thread size for the fill plug on the the pictured master cylinder is m10x1. All references i can find say that it is 1/8 npt, witch it most certainly is not.

This is the right one : https://www.otkshop.dk/shop/bolt-med-o-ring-28374p.html

Yep that’s the one. Was I correct?