ZIP wheels offer the best performance available on straight shaft and die grinders. They are specially formulated to run cool for maximum life. Wheels are free of iron, sulphur and chlorine (Fe-S-Cl) and are guaranteed not to contaminate stainless steel. For notching applications, thickness less than or equal to 1/8 is recommended. For grinding applications, 12 is recommended. Use 24 grit wheels for faster cutting speed and 60 grit for longer life. For use with steel and stainless steel. Package of 25.