Size: 0.6mm 2) Grade: G100--G1000 3) Hardness: HRC 55--65 ... GB, ASTM, DIN, JIS standards 5)good surface Features:Size: 0.6mm Grades: G100, G200, G500, G1000 Materials: Carbon steel, Chrome ... customers' requirements. [sweet hint] By our company production of a kind of high quality carbon steel ball, with special heat treatment ...