Expander ball is drilled to just slightly over the diameter of the stem..it slides on the stem, and is held in place by what looks like a undersized standard expander....

No lube required..
Now if a scientific test to see what the diffrence in runout and neck centering/ stretching would be between cases of known neck runout dimensions using both a unlubed carbide expander and a lubed standard expander, I would like to see that test, but I do not have the equipment to do it