The DEWALT DW8809 4-1/2-Inch by 1/4-Inch by 5/8-Inch-11 XP Grinding Wheel features premium tough zirconia grain for extended life and material removal. The high grain concentration ensures agressive grinding action and smoother running wheels. The proprietary wheel design allows for durable long life wheels, and 3 full sheets of fiberglass for added durability and safety.