Thickness top and bot layer in stackup

Hi, why thickness top and bot layer in stackup PCB equal 0.043 um?

Which file and layer are you looking at?

I looking at P2597_B02_PCB_stackup.pdf in

Drawing units are mm, so 0.043 mm. This would seem approximately correct if you consider the other copper layers are not plated. Plating thickness of 0.013 mm would account for the copper being otherwise the same on all layers, and is probably the same 0.013 mm in any plated-through via.