Abrasive wheels for power-operated grinders; machine parts, namely, grindstones; abrasive instruments, namely abrasive disks for power-operated grinders and abrasive disks for power-operated sanders; machines for sanding floors; orbital sanding machines; floor polishing machines; machine parts, namely, polishing discs for electric floor polishing machines; grinding tools for grinding machines; machine for sanding surfaces; rotary brushes for machines