Miniature Deep Groove Ball Bearings Specifications: 1) Bore size: 3 - 9mm 2) Models: 603 - 609, 623 - 629, 637 - 639, 693 - 699, etc. 3) Series: Z, 2Z, RZ, 2RZ, RS, 2RS, N, NR Inner packing: Plastic bucket Outer packing: Corrugated packing Certification: ISO9002, QS9000, VDA 6.1.