The U series objectives are meant to be used with a universal stage on a polarizing microscope as already mentioned in the previous posts. So the magnification and NA engraved on the barrel only apply when used with the glass hemispheres included with the stage.
The layout diagram is from the patent file for the U5 objective. L1 indicates the hemisphere.
The table is data for the rest of the U series. The numbers in the parentheses indicate data for use without the hemispheres.
Cheers,
John
