Are dimensions of the 10-138 inside or outside?

A handy person from Livonia, Michigan says:
I would like to know if the dimensions shown for the towel bar opening are inside dimensions (inner edge to edge) or outside dimensions (outer edge to edge).

Thank you.
Profile picture of Mike
Mike from SWISCO responded:
Good Morning,

I doubled checked the dimensions of the 10-138 and it is definitely the inside of the towel bar opening. I took a new picture of the towel bar opening to show more detail. Notice that the width is slightly smaller in the center than it is on the top and bottom end. The 5/16" measurement is the width at the smallest (at the center).
Close up view of the towel bar opening of the 10-138
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