My friends with their new iMac wanted to know what other hardware they needed & I recommended a Toshiba Canvio 2 TB USB 3 ext HD to use for Time Machine backups. They bought their copy of Office for Mac in one particular store & were then headed to the place that sells the suggested HD when the salesperson browbeat them into buying a piece-of-shit WD Elements HD.
The side of the box said that it had to be reformatted from NTFS to suit a Mac but when I tried Disk Utility it would not erase or partition the drive, popping up an error claiming some guff about insufficient space.
Whereas the Toshiba drive is sensed by Time Machine and the user is asked if they want it used for backups. They click OK & the Mac reformats it to suit.
The salesperson claimed the WD drive was "exactly the same as" the desired Toshiba unit; a claim I refuted most vehemently as did their son who phoned them while I was onsite.
So they're going to return the junk, get a refund & buy the right one at the other store & save $10 on the deal.