Scotch-Brite(TM) Printed Circuit Cleaning Brush, 4 in x 24 1/2 in x 1 in 6S SFN, 1 per case, Custom General light duty cleaning and deburring applications. Compressed discs adhered to a core. Medium hardness 6 density. Abrasive mineral: Super fine grade silicon carbide. Color: Gray MOS: 4000 RPM