This is a back-up drive.
This is the innards, meaning the actual spinny drive that goes inside the shock-proof case.
This hard drive is 2TB because that is the storage size that fits inside of the shock-proof case.
(If you need more than 2T, as my 2T MacBook Pro laptop does – for some reason the actual back-up requirement is 2.2TB – then get a bigger drive – I get a 5T and partitioned it into 2 segments, to which I back-up alternatively.)
Don’t but this drive if you are not going to buy the case.
You should never carry a hard drive that is not in a case for many reasons, least of which is that the static from the rubbing of your clothes inside your suitcase can damage the data on the drive.
To buy the “Water-proof / drop-proof backup drive enclosure” please go to: https://amzn.to/2PCZBEt