The NEC ND4550A DVD burner was released by NEC in September 2005. CD Freaks has detailled NEC ND-4550A and NEC ND-4551A reviews available. The NEC ND4551 burner adds support for LabelFlash but both drives - together with the ND3550 and ND3551 - share the same hardware and only differ in firmware. Do not try to simply flash a NEC 4551 firmware on a NEC 4550 drive or vice versa. This will NOT work.
Click here for detailed specifications of the NEC ND4550A and ND4551A.
The following firmwares are available for download here:
Overview on the used writing strategies