Before I answer both, a little background about the company.
The MDD or MaxDigitalData brand itself is owned by goharddrive. If you visit their website, you will notice that there is little information about the brand itself, and there is no indication other than that they buy surplus stock and discontinued models from manufacturers . Web is full of negative reviews of MDD with an overall rating of 1 star and there are many Redditors who also talk about their negative experiences.
When there are crazy prices on hard drives, they usually come from either OEMs or very large data centers (we have seen hard drives sold to one of the largest social media companies in the world go to end users). The part numbers differ in these cases. But looking at the failure rates reported by end users, they do not seem to be buying from vendors. If they were buying new devices from vendors, there would not be such high failure rates.
In addition, pricing is too low for a white label. While vendors offer special pricing for OEM business, integrators, and end users, it is unlikely that vendors would offer such pricing for resale at a price that would cannibalize their own business.
We can only assume that these are used drives whose data has been erased . There are already many Amazon users who report enormous power on hours in Smart Info. Other users mention that the drives make noise or fail early, which is usually the case with old hard drives.
That's why we do not sell these drives. We only sell WD, Seagate and Toshiba drives. We also do not recommend that you buy an MDD drive for your NAS. If you really need to buy these drives, check the Smart Info first. SMART is hard to erase (though not completely impossible). You can also use a tool like Photorec to see if there are traces of previously written data on the drive - if the drive was not erased in multiple passes, that would show you traces of data. We advise you to be very careful with this brand