Our mouthpieces are made of a material that has been lab-tested and certified non-toxic, therefore they are completely safe to put in the mouth, as opposed to the "ebonite" conventionally used to make mouthpieces, which contains sulfur. Over time, sulfuric acid is released, giving the mouthpieces a yellowish tint as they age. No such worries with Syos mouthpieces in SCAL3D!