Roller Bearings Marterial: Gcr15 Seal material: Rubber,Ferrum Noise: Z1,Z2,Z3 ... , 6312, 63305, 63306, 63/285) 68 series : 6800, 6801, 6802, 6803, 6804, 6805, 6806, 6807, 68086) 69 series : 6900, 6901, 6902 ... , 69097) Inch size series: R6, R8, EE3, EE48) Specifc designed bearings for motorcycle Double row Tapered roller ...