... wear resistance 4No spots,Shinning as mirror We are specialized in the production of precision steel balls, carbon steel ball ... to ± 1 silk, absolutely guarantee the quality.2. Hardness: hardness in between 55 ~ 623. Imperfect rate: 100% through strict screening, ... believe that we will not let you down ! ApplicationLight duty bearing,conveyer belt,bicycle and automobile parts,slide bearing,caster ...