These white, mounted stones can be used for grinding on various alloys in the dental lab, but they are designed to work best on non-precious alloys. The diameter of the cone shape is These white, mounted stones can be used for grinding on various alloys in the dental lab, but they are designed to work best on non-precious alloys. The diameter of the tapered barrel shape is .17 inches (4.5mm). Each stone is mounted on a handpiece shank (3/32”). Packaged 100 to a box. Made in Korea..31 inches (8mm). Each stone is mounted on a handpiece shank (3/32”). Packaged 100 to a box. Made in Korea.