Fibre Disc ZA-Zirconia Alumina Used for Stainless steel, high alloyed steel (medium polywood, chipboard and MDF plates. & high pressure) grinding of polywood, chipboard and MDF plates. Inner Hole:RoundDepressedCross hole Grit range :# 16,24,36,40,50,60,80,100,120.Available in the following sizes:100mm X 16mm (4” x 5/8”)115mm X 22mm (4.5” x 7/8”)125mm X 22mm (5” x 7/8”)150mm X 22mm (6” x 7/8”)180mm X 22mm (7” x 7/8”)230mm X 22mm (9” x 7/8”)