... as SRL ,PS2, Alvania R12 and so onSeries1.Deep groove ball bearing: 6000series, 6200series, 6300series, 6400 series, 6800 series, 6900 series, etc ... series, UCP series, UCF series, UCFL series7.Self aligning ball bearing: 1200series, 1300series, 2200series, 2300series Ring MaterialChrome Steel ,Carbon steel,Stainless ...