1). Abrasive Flap Disc 4". 2). Grit: 40#---600#. 3). Size: 4",4.5",5",6",7". 4). Usage ... cleaning, deburring. Fitting to used on angle grinder.2). With plastic , fiber-glass and steel backing,and bonded with the abrasive ... . Specification: MaterialSizeGritBackingMax Speed(rpm)Aluminum Oxide100*16mm(4")60#--600#Plastic Backing Or Fiberglass Backing13300rpm115*22mm(4.5")Fiberglass Backing125*22mm ...