Thickness varies according to size.
The paper thickness increases as the grid grows, so the larger paper doesnt flatten or sag or the smaller size is too thick and difficult to handle.It is just the right thickness to match the size of the paper.
85g/m2(B1), 75g/m2(B2, B3, B4, A1, A2, A3), 70g/m2(A4), 50g/m2(B5)