| Inner Diameter | 4 mm |
| Outer Diameter | 12 mm |
| Thickness | 4 mm |
| Model | 638/4-2Z W604 W604-2RS1 |
| Lubrication | Grease or Oil |
| Origin | China |
High-performance miniature deep groove ball bearing with rich stock, 100% on-time delivery, and OEM/ODM support. Suitable for precision instruments and compact machinery. Features high-grade grease technology, low vibration (Z1V1–Z3V3), and versatile transport options.