Toshiba Canvio Advance Portable Hard Drive 4TB Red

It works with my iPad Air 4. Of course, you'll need a usb-a to usb-c adapter (I recommend Belkin) or a hub with a usb-a 3.0 port that works with iPad. And you'll need to format the drive to exFat or Fat32 with a pc or mac because you can't format an external drive with an iPad. All of this isn't too difficult and it's nice having 3.63 TB of external storage for my iPad Air 4. It might seem like a bit overkill but from my experience, you can never have too much hard drive space. Especially if you start recording a lot of 4k videos with the iPad Air 4. Plus, this drive came in my fav color (red) so that's an added bonus.