... ,125mm,150mm,178mm, Material: Aluminum oxide Flexible grinding disc,radial flap disc Diameter X Hole sizeGrit No. 364060801001201501802220 FLAP DISCS100MM ... by different abrasive: 1)Aluminium oxide, (A.O.)Suitable for iron, mid steel, welding rods, cost iron aluminium, ... ferrous metals and wood.2)Silicon carbide (disc in black color ), (C.)Suitable for marbles, stones, building materials, hand materials ...