Scotch-Brite(TM) High Resolution PC Cleaning Brush, 4 in x 24 1/2 in x 1 1/4 in 6S SFN, 1 per case Consistent, aggressive cleaning and deburring action. Compressed, resin bonded discs adhered to a core. Medium hardness 6 density. Abrasive mineral: Super fine grade silicon carbide. Color: Gray MOS: 4000 RPM