Square edge wheels with uniformly, interspersed air pockets run cooler allowing you to work longer without burning your fingers. Airflex Wheels are excellent for all precious alloys including platinum, titanium and stainless steel. Made of a silicon carbide abrasive combined with a flexible silicone rubber. Maximum speed 5,000 - 10,000RPM. Medium, Green, 7/8" x 1/8" (22x3mm). 12/pk.