O2 Sensor

Hi, I have a 961 SF 2015 with around 20K kms and I need to replace the O2 sensors but not sure about the fitment option. Bosh has one called “Magnum Motorcycle Bosh O2 Oxygen Sensor Universal Wiring” but there are 2 options for fitment:
- M12x1.25mm oxygen sensor
or
- M18x1.5mm oxygen sensor

Does anyone here knows which option is the correct one?

Thanks,

Sergio

P.S. I am from Sydney and there isn’t anymore a Norton dealer in Australia.
I contacted Norton UK directly a week ago and still waiting for a reply.

The threaded hole in the exhaust pipe is M12 .

Thank you TonyA