... 2.Stainless steel:AISI440C, AISI304, AISI316 3.ABEC-1 ABEC-3 ABEC-5,ABEC-7 4Noise level:Z1,Z2,Z3,Z4 High Performance ... low noise miniatrue stainless bearings1.Model:Open,Z,2Z,RS,2RS,RZ ... .PaypalServiceOEMStaff spititBeing United,Realistic,Pioneering and Innovative5.Welcome to inquiry . High Performance low noise miniatrue stainless bearings