Flap disc, high density "Jumbo" blue zirconia, 40 Grit Type 29, depressed center 4-1/2 inch with 5/8 inch-11 arbor ZA40, for right angle grinders. Cuts fast and outlast sanding discs 10-to-1. Great flexibility. Ideal for rough or fine finishing. High density discs are ideal for the extra tough jobs. Long lasting, cooler running Jumbo style.