?Durable, safe, and firm, wear-resistant, high elasticity and grinding efficiency, low noise, and long wheel life. These welding accessories and tools 4 1/2-inch grinder sanding discs are built with top-grade hard zirconia, offering unmatched durability for virtually indestructible grinding. Their industrial-grade, high-density premium zirconia construction ensures exceptional strength, making them the go-to choice for high-performance grinding wheels. The set includes 40 discs with 40/60/80/120 Grit, catering to versatile grit applications. These indestructible angle grinder sanding discs are suitable for various tasks, from metalworking to woodworking, concrete grinding, and more. With a maximum RPM of 13,300, they provide exceptional value and performance while adhering to safety standards. Designed for T29 angle grinders, they are compatible with angle grinders or die grinders such as Makita, DeWalt, Milwaukee, Tack life, Bosch, Craftsman, and Black and Decker grinders, and compatible with a wide range of materials and applications.