Seems to be 3/4" oak(?) plywood, mitred and i guess glued and pinned together. Strange thing the previous owner, who installed this, went to college for carpentry and his father built the house, but i think he was a bit retarded. I even found some old drafting charts with his name on it in the basement. And no there is nothing inside the pillar. I guess i would use the jack post then replace it, i need to match the finish with the other post i put in. Or would you just leave it?