Superfine ranges from grade 500 to 600. Flexible foam pad enables user to sand hard-to-reach areas such as headlight openings, around door handles, door jambs, etc. Helps to eliminate finger marks and can be used wet or dry. 3M™ Softback Sanding Sponges are coated with aluminum oxide mineral. Each grade uses a range of mineral sizes. Superfine ranges from grade 500 to 600.