Miniature ball bearings are designed for compact applications, offering smooth operation, low friction, and low maintenance. Ideal for high-speed and precision requirements. Common applications include robotics, medical equipment, electronics, aerospace and aviation, automotive, precision instruments, hobby and RC models, and more.
| d | 4 mm | Bore diameter |
| D | 9 mm | Outside diameter |
| B/B1 | 2.5 mm | Width |
| d1 ≈ | 5.2 mm | Shoulder diameter inner ring |
| D1 ≈ | 7.5 mm | Shoulder diameter outer ring |
| r | 0.1 mm | Chamfer |
| 7 pcs | Ball qty | |
| 1.5875 mm | Ball diameter | |
| ≈m | 0.65 g | Weight |
| Cr | 545 N | Basic dynamic load rating |
| C0r | 226 N | Basic static load rating |
| 53000 r/min | Max speed (Grease) | |
| 63000 r/min | Max speed (Oil) | |
| P0(ABEC-1) | Tolerane | |
| CN | Clearance |
| Open | Sealing | |
| None | Locating feature outer ring | |
| 52100 | Ring Material | |
| 52100 | Ball Material | |
| SPCC | Cage Material |
| NMB | NHBB | NSK/ISC | NTN | BARDEN | RMB | MPB(TIMKEN) | SKF | ADR | GRW | EZO | DYNAROLL | FAFNIR | FAG | Gost | others |
| L-940 | 684A | 684 | 684 | UL409 | UL40C | 618/4 | AX4 | 684 | 684 | MR618/4 | 1000084 | 684 |
