My Book Essential Power Adapter Lost

I have an old My Book Essential and I lost the power adapter. The external hard drive is 2 TB as I remember and I searched in the market for power adapters but it looks there are many standards.

Does anyone know what is the size and amp rating for this hard drive?

WD My Book Essential USB 3.0 P/N WDBACW0020HBK-01

I saw in some pages the rating is 1.5A and 12V DC but it does not show the size.

There are several sizes e.g. 5.5x2.5mm , 5.5x2.1mm and 4.0x1.7mm which one suits this hard drive?

The WD My Essential is 12V DC / 1.5A / 18 WATTS

As for the size … i measured the width and inner of the plug adapter with my vernier caliper

width is 5.5MM and inner is 2.1MM … which is virtually standard for all WD External Hard drives

ie. I can use a WD External Power Supply on a variety of my WD drives (My Cloud, My Book, Elements etc) … and the socket fits perfectly on all models