Polarity of HP external hard drive

[darryl22]

Hello,
I'm trying to find the polarity of my western digital "My Book" external hard drive 500 GB. It isn't shown on the drive nor does the literature show it

 

[WyomingKnott]

Unless you have lost the power supply, you could either read what is stamped on the outside of said power supply or attach a multimeter to it.

Again "unless you have lost the power supply," why do you need to know this? Not challenging you, I'm just curious.