Revitalize your Sioux valve seat grinder with this comprehensive set of 40 restoration grinding stones, designed to enhance precision and durability in your automotive maintenance tasks. Crafted to fit seamlessly into Sioux stone holders with a thread size of 11/16", these grinding stones ensure a snug and secure fit for efficient operation. Each stone is meticulously engineered for optimum performance, promising exceptional results in valve seat restoration projects. Elevate your workshop's capabilities with this high-quality set, indispensable for professional mechanics and automotive enthusiasts alike.