... the Aluminum content or the Caron content:1.Ferro Silicon (standard grade)Si 75%min., Al 1.5-2.0%max ... :10-50mm,50-100mm or as required.2.Ferro Silicon (standard grade)Si 72%min., Al 1.5-2.0%max ... :10-50mm,50-100mm or as required.3.Ferro Silicon (standard grade)Si 70%min., Al 1.5-2.0%max ... Size:10-50mm,50-100mm or as required. 4.Special grade Ferro Silicon 1) All in Special Grade2) Low Aluminum Grade3) ...