Dell has just announced a pair of external SSDs. The Dell SDI T0500 will have a 500 GB capacity. The Dell SDI T1000 will, as the name suggests, doubles that to 1 TB. Both external SSDs connect via Thunderbolt 3. Because it’s using this connector, we can expect it to be fast but not mass-market. I am guessing that Dell intends this product to be purchased with one of their Thunderbolt 3 laptops, and probably with a specific type of user in mind. That is just my speculation, though.
Unfortunately, we don’t have much else to go on. No price, availability, read or write speeds, IO throughput, or anything else has been published.