Just put some calipers on mine.
The saddle, from flat to flat is 33.1 and is symmetrical top to bottom.
So, 33.1-25.4= 7.7 halve it gives 3.85mm.
Which looks about right by direct measurement, but I can't get the calipers on precisely with the scope in the mounts. That figure is as good as I can do with it mounted, if the dimension is critical I'd recommend a second opinion.