This is a 240 grit, long-lasting open-pore polishing wheel for cool trimming and effective polishing on silver, platinum, titanium, stainless steel and precious metals. Tiny pockets of air are uniformly interspersed throughout the AirFlex wheel, so it grinds and polishes quickly without overheating the workpiece. The work stays cooler, so you can work longer without burning your fingers.AirFlex works equally well on all precious alloys, including stainless steel and titanium. Flexible AirFlex follows contours and leaves a smooth, uniform finish. Made of silicon carbide abrasive in a silicone rubber bond. Measure 4" diameter x 19/32" thick with 1/4" arbor hole. Max. operating speed: 3,000rpm. (Also available in 7/8"). Made in Romania.