| Manufacturer | Part Number |
|---|---|
| Fischer Bearings | NUM20 |
| NSK | NU304 ET (NSK) |
| SKF | NU304-EC P (SKF) |
| ZKL-ZVL | NU304 |
| SKF | NU304NA/WM043 |
| KOYO | NU304 (KOYO) |
| SNR | NU304E G15 (SNR) |
| SKC | 3007866 |
| Fiat | 333170 |
| GPZ Bearings | 32304 |
| NTN | NU304E |
| Marlin-Rockwell Corp. | MR304E |
| Ducati | 98.1M1001/6 |
| Rollway Bearing Co. | MUC-304 |
| Norma-Hoffmann Bearings | R-320-E |
| RHP | NU304 |
| SNR | NU304 |
| ZF | 0635410056 |
| SKC | 5967980 |
| SKF | NU304 (SKF) |
| RIV Officine di Villar Perosa | 5DBVP20 |
| Bower Roller Bearing | MA1304EL |
| Lamborghini | 8/11 |
