They are very durable. Professional General Purpose Metal CuttingThin. 045-Inch wheel design for quick burrs for any trimming. Proprietary alumina grain blend for aggressive cutting. Proprietary material blend provides durable wheels with long life.2 full sheets of fiberglass for durability and safety. Maximum RPM: 15200.Main Features【25 PACK】This applies to a pack of 25 pieces of our cutting discs.【Material】Proprietary combination of alumina grain for aggressive cutting.【Application】These cutting discs are designed for cutting fiberglass, steel, iron, plastics, stainless steel and other ferrous metals.【Safety】Please wear all appropriate protective equipment (eyes/ears/face/hands/body/etc.) when using these discs. SpecificationsMaterialAlumina + Resin OxideScope of ApplicationMetal Stainless Steel Cutting WheelPackage Contents5 Wheel Cutting ×NoteDue to manual measurement, please allow slight measurement deviations. Due to the different display and lighting effects, the actual color of the item may be slightly different from the color displayed on the picture.