The NEC ND2500A was released by NEC at the end of 2003, followed by the ND2510A in 2004. You will also find ND2100A drives which all share the same hardware, but differ in firmware to disallow DVD-R or DVD+R-DL writing.
There is a NEC drive conversion tool to convert ND2100A into ND2500A/ND2510A drives, but you need to flash a 2500/2510 firmware after conversion. According to NEC the ND2100/ND2500 drives do not have the necessary calibration for writing double layer discs but there are no known issues from people not able to burn these discs.
On CD Freaks you can find a detailled NEC ND-2500A review and a review of the LaCie d2 which is an OEM version of the NEC ND-2510A.
Click here for detailed specifications of the NEC ND2500A
The following firmwares are available for download here:
Overview on the used writing strategies