No spanners required. 100% of sanding disc can be used. Can be removed and re-applied. Unaffected by dust or moisture. Aluminium oxide abrasive ‘resin-bonded over resin’ to Hook-n-Loop backed paper .To suit Flex, Kress, PEX15, PEX9.6. Suitable for wood, plastics, ceramics Hook & Loop Fixing. Aluminium Oxide. Hole Pattern: 600A - 6 Holes.