Tough zirconium grain provides fast grinding and reliable finishing performanceDurable cotton backing for long lifeExceptional value and performanceContaminant Free (Fe + Cl + S < 0.1%)Type 29, Flap discs are constructed by layering coated abrasive flaps so they wear away and expose new, sharp grainFlap discs increase productivity and reduce total grinding and finishing costs by grinding, blending & finishing in 1 stepFiberglass backings will wear uniformly with abrasive cloth and will not splinter or smear on the workpieceFiberglass backed flap discs are designed for a lighter, quieter operationEncore is also available in a Type 27 Shape