I really don't want to get into a debate about the quality of HDDs - my NAS has been woorking fine on WD blues for 5 years and in any event even though I have Raid, I back up to an external drive regularly. In fact I have had a Mycloud as well for the same number of years and that has just failed - guess what the - HDD is a WD RED!
Clearly no none can answer the actual question so I am going to buy one take it apart and see what's inside (It will almost certainly be a Seagate or WD) the only issue is is the controller board - USB or SATA - I've seen plenty of 2.5 drives with a USB controller but never a 3.5 they are normally (these days) SATA.
Thanks everybody for your input.