3M Fiber disc 501C features sharp alumina zirconia mineral on a durable fiber backing, making it ideal for weld removal and other medium pressure applications such as deburring or rust removal. Alumina zirconia offers a fast cut and consistent finish on mild steel yet can also be used with good results on stainless steel. - 3M Fiber disc 501C a heat resistant resin bond design to provide durability and long abrasive life for demanding operations such as edge grinding. Alumina zirconia features frequently to continually produce sharp points and deliver a faster cut-rate than aluminum oxide.