I think this is made from Oak, i left it rather thick at 5-6mm due to the weak wood on one of the sides, its 5cm high and 9cm wide, i used sanding sealer and then finishing oil
I like the bark that's still in place. Looks like you got lucky with the point on the right side of the gap. On the left side it could get really ugly trying to sand it on the lathe. At least that's what I've heard.