Where it comes from : When introducing this products, some salesmen often misleading the customers deliberately or inadvertently by saying that it is a newly designed product or a slag. Actually it is a by product comes from silicon metal plant. It deposits on the bottom of the melting furnace, and has to be cleaned out in months interval. But with technological development, the interval has prolonged from three months to six months. So the output of this product is limited. We collect and select this product from bigger Silicon metal factories all around China. 68/18,70/22,65/18 we all can supply