Camel CGW brand 4 1/2" diameter high performance grinding wheels are made of Zirconia and Aluminum Oxide grain, allowing for faster and smoother grinding as well as an extra long wheel life. Available with a depressed center (Type 27), 1/4" thickness, 5/8" arbor with a hub. ZA24T bond design. Grain Size: Course Grade: Hard Applications: Great for steel, cast iron and stainless steel. For angle grinders.