It's only the microns the brain has to deal with. It it not good for your imagination.
Looks like you might now use 25.4mm and 9.52mm cutters. It is just a number.
Just becoming accustomed to the standard sizes used. It is very dependent on the industry you are in, for what you will find/come up against.
Just think in metric and write in inches.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.