To add an additional unit type, navigate to the "Fields & Equipment Types" tab of the Project Configuration page. Expand the "Additional Unit Types" section and click the "+ Add" button.
Once added, the new tab becomes available to enable equipment fields.
If you have major tags enabled, you may choose to link the new grid strictly to the major tag, OR to enable the "Tag Number" field. If enabled - the new unit type will be linked to a unit from the Tagged Equipment grid.