The Welland ME-747J connects one disk via USB or eSATA. The main advantages are low cost and no fan.
You have a disk you want to connect temporarily. Using a USB case saves you opening your computer. The Welland ME-747J fits the purpose. There is no fan which means you can use it in a dusty environment without anything clogging up. You can have it sitting next to your head without a noisy fan distracting you from your work. When you finish copying files to or from the disk, you take the disk with you to the next computer.
As a backup device, the Welland ME-747J has the advantage of being easy to remove when you are finished. You could finish work by backing up to the device then moving the device to a fire proof safe.
eSATA is faster than USB and is only on new computers. When you are transferring from an old computer to a new computer. you can backup the old computer using the USB connection then connect to the new computer using eSATA. Do not limit yourself to a USB disk without eSATA.
When one disk breaks, you want a backup on a second disk. If all your disks are the same age, brand, and used in similar circumstances, you can have more than one break at the same time. backup to several devices. You might backup your computer to an eSATA or USB disk then have a backup program replicate to another USB disk. USB cables can be longer than eSATA which means your second USB disk could be in another room.
The whole building could catch fire. USB disks can easily be moved to a fire proof safe. With the low cost of the Welland ME-747J and large disks, you could have several that you use in rotation between home and your office. What are the chances of both your home and office burning down at the same time (assuming your office is not a room at home).
Network Attached Storage
Many NAS devices include USB connections for additional storage plus they can run scheduled backups. You can add the Welland ME-747J as additional storage and set your NAS device to backup to the Welland ME-747J. My NAS appliance has two disks in a RAID 1 array and has two USB ports for additional storage. I have an older USB disk, similar to the Welland ME-747J, connected to backup the NAS.
Choice of disk
There are a lot of USB disk devices supplied with the manufacturer's choice of disk. The Welland ME-747J gives you the choice of disk including using one of your existing disks.
Consider one Welland ME-747J for a quick backup of your notebook computer and for any work involving bulk file copying. I-Tech have Welland products at a good price and with reasonable delivery costs in Australia.