where is the gap set when creating voids in static copper

I have a couple of filled static shapes that were created using a mechanical editor and imported as dxf.

I then use the 'Shape Void Element' to create voids in the large shape from the smaller shape. But I noticed that the void is backed off from the smaller shape by a set amount.

I want to know where it distance is set? Is this set from the Constraints Manager? Which setting is it that is used?