matiral :chrome steel ball grade:G40-G2000 standard:ISO9001:2008 hrc:60-66 application:bearing,bicycle and automobile parts matiral :chrome/bearing steel ballgrade:G40-G2000standard:ISO9001:2008hrc:60-66property:magnatic,ferritic,iol packingapplication:curtain ,bearing,bicycle and automobile fitting,valves,sprayer the hot sales bearing steel ball of curtain