Oki B 4250 - Manual (Page 14)

PRINTER COMPONENTS > 14
17. Power cable connection
18. Cooling fan
19. USB interface connection
20. Parallel interface connection (not available on B4100)
21. Second paper tray (optional) connection (not available on B4100)
22. Network card (optional on B4350 only)
23. RS232 serial interface card (optional on B4250, B4350, B4350n)