for making flap wheels, flap discs and abrasive belts,sanding wood, metal, plastics Model Number ... Backing Grit Roll Width (mm)UsageApplicationGXK51(For Flap wheel) aluminum oxideX Cotton P36- P600 800flap wheels, flap discs, belts, rollsgeneral purposes for wood ... GXK51-B aluminum oxideX Cotton & Polyester P36- P400 1400belts,flap discs general purposes for wood working, metal working, and plastic ...