OK. I searched for this info before I bought and google did not provide the answers on the day, so I’m adding this info to the web in the hope it will save someone a little bit of hassle.
I was ordering a goodridge pressure switch to replace the back brake light switch on the Suzuki bandit 600n 1995 mark 1. But screw thread size or rather the thread pitch got a bit confused. Seems Suzuki are in the habit of having a finer thread on the master cylinder end than they have on the brake caliper end. It is my understanding that most other manufacturers use the same thread size and pitch on both ends.
Bottom line.
The stock 1995 bandit GSF600n uses a banjo bolt of a 10mm thread with a 1mm pitch on the master cylinder end and a 10mm thread with a 1.25mm pitch on the brake caliper end. I used a short thread option switch and it fit just fine on my stock master cylinder although I did add some flexible conduit protection to the cable as it is right in front of the back wheel. The one I got came from here.