A-Prime Premium Cut Is The Top Selling Flap Wheel Material In The World. It’S A Flexible X-Weight Material With A Premium Initual Cut Rate. Flexible Flaps That Excel On Working On Hard To Reach Areas. Superb For Finish-Sanding Of Small Wood Or Metal Contoured Parts, In Or Around Radii Or Into Holes. Use On Stainless Steel, Steel, Alloyed Steel, Nonferrous Metals, Aluminum, Titanium And Glass.