ALUMINUM, BRASS, CAST IRON, MILD STEEL, METAL, STAINLESS STEEL CUT MATERIAL; BI-METAL BLADE MATERIAL; 2-1/2 INCH DIAMETER; 205 RPM (ALUMINUM), 180 RPM (BRASS), 90 RPM (CAST IRON), 65 RPM (TOOL/STAINLESS STEEL), 135 RPM (MILD STEEL) SPEED RATING