The MMJGRIND  is based on FDA approved and Bio-Compatible materials. We are have tested a few materials to find the most suitable material for the application. Our real goal was to find a material that would be both mechanically and economically fit.It's not only the material that counts but also the colors added to it. While most color pigments are not approved for medical purposes we always prefer to avoid any additives at all.Ring material - P.O.M Grinder material - PC