This is a very good question.
From the pictures on the link the pieces are glossy looking like a bakelite kind of plastic. The cost of the set is relatively low also making me think it is some kind of plastic kind of material. I see they have the same set, at the same price in a "Metallic" version. Once again I bet this is some kind of plastic from this viewpoint.
I Googled "Woodtek" and the vast majority of the results talked about a brand of wood working equipment. After a couple of pages of this I went onto other things.
Recently saw a new arrival from HOS and the set looks great. Love the grain of the white pieces but I have no idea where it is made and what it is made from even after reading the details of the set. Anyone out there know anything about "woodtek"?
http://www.houseofstaunton.com/the-candidates-series-chess-pieces-4-25-king-woodtek-18511.html