Which power supply, 12v 2A or 12v 1.5A?

Hi friends. I have some 2tb external “My Book Essential”. there are usb2 and usb3 both.

I have some other external HDDs from other companies.

as I have many power supply (some 12v 2a and a few of them 12v 1.5a), I don’t know which adaptor is suitable for any hdd.

so I use 12v 2a adaptor to most of them.

my question is this can damage hdds?

If yes, which adaptors I have to use for 2tb My Book Essential (usb2 , usb3)?

Thank you

This link http://wdc.custhelp.com/app/answers/detail/a_id/1378/session/L3RpbWUvMTMyMDE3MTc3OS9zaWQvak9TMVcxSWs%3D shows the adapters.