With 4 TB of storage, this is a good hard drive if you need a larger storage unit. The form factor is 2.5" which apart from this model is commonly used in SSD drives.
From Amazon
ADATA AHD650-4TU31-CBK DashDrive Durable HD650 - Hard drive - 4 TB - external (portable) - 2.5" - USB 3.1-256-bit AES - black - (Storage > External Hard Drives) -)r
Clove Technology
ADATA HD650 external hard drive 4 TB
Athema Services
adata 4tb dashdrive hd650 usb 3.0 black. moq 5 pcs. ahd650-4tu31-cbk