California Proposition 65: This product contains a chemical known to the State of California to cause cancer. Flap Disc, Type 29, Disc Diameter 4 1/2 in, Mounting Hole Size 7/8 in, Abrasive Grit 36, Abrasive Grade Extra Coarse, Abrasive Material Zirconia Alumina, Series Tiger (R), Max. RPM 13, 000 RPM