ALUMINUM, BRASS, CAST IRON, MILD STEEL, METAL, STAINLESS STEEL CUT MATERIAL; BI-METAL BLADE MATERIAL; 3-1/4 INCH DIAMETER; 155 RPM (ALUMINUM), 140 RPM (BRASS), 70 RPM (CAST IRON), 50 RPM (TOOL/STAINLESS STEEL), 105 RPM (MILD STEEL) SPEED RATING