1) Material: chrome steel 2) Metric series: 32004-32030, 33005-33024, 30202-30238, 32203 ... 30330 1) Material: chrome steel or stainless steel2) Metric series: 32004-32030, 33005-33024, 30202-30238, 32203-32240, ... 30330, 32303-32330, 33205-33220 and 31303-313303) Inch series: LM11749/10, LM11949/10, LM12749/10, LM12749/11, ... Quality control: according to European standard Standard Taper Roller Bearings