here is some information about which to choose. seems to make sense to me.
The Onefinity Woodworker with Masso controller (part of the Elite series) supports both inch and mm Vectric post processors, such as “Onefinity Elite Masso - inch” or “Onefinity Elite Masso - mm” (or similar variants like “Masso ATC Arcs (inch)” and “Masso ATC Arcs (mm)”).Choose the post processor that matches the units used in your Vectric project setup (e.g., VCarve or Aspire drawing/job units):
If your project is designed in inches, use the inch version.
If your project is designed in mm, use the mm version.
This ensures the generated G-code has the correct scale and unit mode (G20 for inches or G21 for mm) for accurate machining. The Masso controller handles both seamlessly, but mismatching the post processor to your project units will result in incorrect part sizes.