I just pulled out my UB-1 Eddy Finn. It is bone. Neither Corian or plastic drag on your teeth as does bone. All of the wooden ukes openly state bone nut and bridge. I just dragged my teeth on my soprano E/F. It is the same feeling. I need to talk to my salesman tomorrow..if I find out any differently I will update the post. I did notice the wood ukes have a bevel on the lead edge of the nut, but the banjo ukes are square cut. Another question for tomorrow.. why?