This HERCULES™ 4-1/2 in. x 5/8 in.-11 120-Grit Type 29 Flap Disc is constructed with a premium blend of tough Ceramic Alumina abrasive that works up to 2X faster and lasts 4X longer than aluminum oxide wheels. The durable flap plates flex under pressure for grinding and blending on curves and contours. This disc delivers professional results on carbon steel and stainless steel applications.