United Abrasives-SAIT 20146 Type 27 4-1/2-Inch by 1/4-Inch by 5/8/-11-Inch Attacker Depressed Center Wheel, 10-Pack High performance, ceramic aluminum oxide grain Very uniform, high density grain structure is extremely durable Extremely fast stock removal 1300 - 4000 /RPM 1-Inch Arbor