Thanx @warzkelly, I suspected as much. Since I'm still waiting for them to ship from WA, I didn't have the headstock to measure. I was going to use some American Black Cherry that I had to add to it so I could re-shape it, but it's 19mm thick. Didn't want to cut a piece of my White Oak, but I guess I could....that's 16mm. I paid a vist to my local Carbatec. They had some small pieces of various timber. Was hoping for some maple. they had Pacific Maple... a bit too weak I think. The birdseye maple just seemed a bit pricey. I ended up walking out with some New Guinea Teak, and some Silkey Oak veneer. I think a larger piece of New Guinea Teak would make a nice tone wood.... holding the bit I had lightly and giving a tap pronounced a surprising ring!