The material of the grinding wheel guard shall use rolled steel with the following mechanical properties:1. Tensile strength being over 28 kilograms per millimeter square and elongation over 40 percents.2. The sum of the tensile strength (unit: kg / mm2) and the value of the twice elongation (unit: percent) being over seventy six.The material for a portable grinder guard or a non-band guard shall be that based on the highest using peripheral velocity in Attachment table 26 regardless of restrictions in the preceding paragraph.The material of the guard for the cutting-off grinding wheel with the highest using peripheral velocity below 80 meters per second can use aluminum with tensile strength below 18 kilograms per millimeter square and elongation over 2 percent regardless of restrictions in the two preceding paragraphs.Attachment table 26.pdfAttachment table 26.doc