This is a 4TB, USB 3.0 (large and fast) drive that is perfect for backups. Once you open this on Amazon you will see boxes to choose smaller sizes if you are told you can get a smaller drive.
Note: DO NOT move your data to the backup drive and just store it there. If you move your data/documents to a drive then it is no longer a backup drive. “Backup” implies it is a SECOND copy.