Replacement power supply for WD MyBook Duo

I need to find a replacement power supply for my MyBook Duo disk enclosure. I have received conflicting information about the spec of the connecting jack. It is either 5.5x2.1mm or 5.5x2.5mm but I am not sure which. Can anyone set me straight?

Hi,

Here is the AC Adapter Specifications for My book Duo drive:

12 Volts
3.0 Amps
36 Watts

Please refer to this link in order to purchase the drive power adapter: Power Adapters for WD Products