... and bearing steel ball , for 13 years in China, has earned trust from our customers in North America, Europe and Asia, Middle ... to ± 1 silk, absolutely guarantee the quality.2. Hardness: hardness in between 55 ~ 623. Imperfect rate: 100% through strict screening, ... ,slide bearing,caster wheels,computer peripheral products,toys,metal milling,hand tools and etc. G500 soft carbon steel ball made in china