... G1000,G2000 3.material : AISI1020 Material ASTM/AISI 1020Feature:High hardness with a soft core giving resistance to shock load ... 60mmGrade Available:G100, G200, G500, G1000, G2000Application: Moderate loads and allow rotating parts, for example: castors, conveyors, roller skates, ... , etc.CertificationISO 9002: 2000OriginalShandong province , China AISI 1020 LOW CARBON STEEL BALL (0.5MM-100MM)