From the "FieldLab Desktop" menu, select "Preferences"

Under the "General" tab, select the "Custom Units" button.

In the Custom Units dialog box, choose "New" for a new unit, "Edit" to edit and existing unit from the list.

Edit the settings of your Custom Unit.
- Custom Unit Name: Enter the name of your Custom Unit here.
- Units the custom is based on: Select a standard engineering unit you would like your Custom Unit to be relative to.
- Base Units: Enter the low and high for the standard engineering unit your custom units will be based on.
- Custom Units: Enter the Low and High for your Custom Units, relative to the Base Units.
- Plot Button: Optional button that shows a visual representation of your Base Units and Relative Units.
- Save: After completing your Custom Units, Save the data and you'll be returned to the Custom Units preferences window.

Add Custom Unit to a Test
Navigate to Tests Modes in FieldLab Desktop

Select an existing test, or create a new one.

Select the Custom Unit from the Units Field.
Edit or create a new Test and add your Custom Unit in the Test Mode Units dropdown menu.
If you have this Test Mode on a FieldLab already, you will be prompted with a reminder to sync all FieldLabs with new the Test Mode data.