radial ball bearing 1621rs:1,ABEC-3,5;Z2V2,Z3V3 2,High speed ... :Z1,Z2 5,C2,C0,C3... Lily bearing is a specialized manufacturer of radial ball bearing 1621rs.Features:1),Shield / closure: Open ... 6mm to 80mm8),Outside Diameter:from 15mm to 100mmbicycle bottom bracket bearings