4-1/2 Inch x 7/8 Inch x 5/8 Inch 40 Grit Zirconia Alumina Type 29 Radial Polifan Sgp Zirkon-Curve Abrasive Flap DiscPOLIFAN CURVE is a PFERD innovation designed to quickly achieve a smooth, consistent surface finish on fillet welds. the unique radial construction shape (PFR) offers a superior solution for this common task. the POLIFAN SGP CO CURVE is designed for demanding grinding, especially for achieving fine surface finishes. the top sized ceramic grain guarantees cool grinding on poor heat conducting materials, without thermal damage to workpiece.