... authentication ISO 9001:2000 4.Hardness 62-65 high quality ceramic bearing skateboard Bearing typeDimension(mm)Rated dynamic load(KN)MAX ... SeriesSeries 6000, 6200, 6300, 6400, 62200, 62300, 6900,16000,etc. Ring MaterialChrome Steel ,Carbon steel,bearing steel Tolerance gradeGB/T307.1 ... and gland 6.Noise inspection 7.Appearance inspection high quality ceramic bearing skateboard 61802