Mexco RBX Radius Blades are designed to be used with 4.5″ and 9″ angle grinders for cutting curves and radii with ease. The radii of the curve can be altered by tilting the angle of the blade in the cut. These products are especially suited for cutting into concrete, natural stone and paving slabs, making them ideal for landscape gardeners, driveway installers, general builders and anybody doing decorative patio work.