The SanDisk Extreme Portable SSD is available in 500GB, 1TB, 2TB, and 4TB.
From my experience using the URSA 12K, I recommend you go with at least the 2TB option. I’ve gone with the 4TB and find that to be much better for my needs of regularly shooting sports.
There's certainly other options out there for SSDs, such as getting Blackmagic's own URSA Mini SSD Capture Device for 2.5" SSds. But this is certainly a very expensive option—more expensive than getting an entire 4TB with the SanDisk Extreme Portable SSD!
This also doesn't include your costs of also having to buy a 2.5" SSD to go with this adapter.
One of the most trusted brands is Samsung, and the best option they offer is the 870 EVO 4TB 2.5" SSD might look like a good companion to the Blackmagic Recording Device, but the most important thing you need to consider is read & write speeds of the SSD.
The Samsung 870 EVO 4TB 2.5" SSD:
But that's simply not enough write speed for the URSA 12K to write data onto the drive.
According to Blackmagic Design's website, the URSA Mini Pro 12K needs about 1,000 MB/s of write speed if you're going to take advantage of all of the recording modes such as large resolutions and high frame rates.
Let's compare that to the read & write speeds of the SanDisk Extreme Portable SSD:
However, it's only fair to you that I now mention the downsides. ⤵
Cutting to the chase, the biggest downside is using a cable.
It doesn't matter how robust the cable is, it's still an unsecured, loose piece of equipment that can easily get hit, damaged, or simply loosen over time.
There are just more points of failure.
However, if that doesn't scare you off, and the price sounds enticing, you may very find the SanDisk Extreme Portable SSD is a great fit for you.
Camera: URSA Mini Pro 12K
Battery: Reytric 300Wh V-Mount
Editor: DaVinci Resolve Studio
Light: Aputure LS 300X