... trademark steel balls in various sizes. A. Stainless steel ball:AISI440(American),9cr18(Chinese),degree of hardness amounts to 55 ... so on high precision mechanical fitting.B. Stainless steel ball:AISI316L(American),Ocr19Ni12N02(Chinese),degree of hardness≤30°,Diameter:1 ... so on has certain corrosive product.C. Stainless steel ball:AISI304(American),Ocr19Ni9(Chinese),degree of hardness≤30°,Diameter:0 ...