Our take
The STJD500400 is the small, cable-connected choice here for someone who wants an external SSD with USB 3.0 and modest 500GB capacity. It is easier to carry than a powered desktop drive, but the vendor's up-to speed is not a measured result, current Amazon identity is unverified, and the limited capacity may not suit a large archive.
Carrying a modest working set between compatible USB computers without a separate power adapter.
Buyers who need several terabytes in one device, a verified current offer or warranty, or a proven performance number for a particular computer.
Pros & cons
What could work for you, and what to consider before buying.
What works in its favor
- Seagate confirms the exact 500GB STJD500400 model as a solid-state Expansion drive, distinct from Expansion HDD models.
- The listed 75 by 55.5 by 10mm body and 131g drive weight describe a compact unit without implying rugged protection.
- USB 3.0, stated USB 2.0 backward compatibility and bus power support a simple one-cable portable setup.
What to weigh up
- The 500GB capacity is limited for a large multi-terabyte media archive or a broad system backup.
- The listed 400MB/s maximum is not a guaranteed result for every computer, file pattern, cable or drive condition.
- The included 20cm cable may constrain placement, and Time Machine use may require reformatting the drive.
The key details
| Model covered | STJD500400 |
|---|---|
| Advertised capacity | 500GB |
| Drive configuration | Portable solid-state drive |
| Host connection | USB 3.0, backward compatible with USB 2.0 |
Performance figures are manufacturer claims. Source checked October 6, 2026. Regional models and included accessories can differ.
What the features mean for you
A compact SSD for everyday file movement
The STJD500400 is an external solid-state drive, not a mechanical hard disk. Seagate maps the model to 500GB and describes its Expansion SSD as small, light, and intended for portable storage. The datasheet lists a 75 × 55.5 × 10mm body and 131g weight, which gives a concrete sense of its carry size without implying that it is indestructible. It can suit someone moving a working set of documents, photos, or project files between compatible computers. Its 500GB capacity is the first practical constraint: measure your actual data set rather than treating the SSD label as a reason to buy.
Check the connection and the speed claim
Seagate specifies a USB 3.0 port for USB 3.0 transfer rates and backward compatibility with USB 2.0 at USB 2.0 rates. That makes the host port an important part of the purchase. B&H's exact-MFR listing gives an “up to 400 MB/s” figure; that is a published maximum, not a result we measured and not a guarantee for every cable, file pattern, computer, or drive condition. If an old computer only provides USB 2.0, the drive can still connect according to the datasheet, but it will operate at the older interface rate. Confirm your port and cable before expecting the highest published transfer claim.
Portable power, with a cable to keep track of
B&H identifies this model as bus-powered, and Seagate lists a short USB 3.0 cable in the box. That avoids carrying a separate power brick, a useful difference from the two desktop-oriented products in this small group. The tradeoff is that a cable remains part of the setup, and a 20cm cable may be awkward if the computer's ports are crowded or positioned behind a display. The manufacturer dimensions and weight describe the drive itself, not the whole carry kit. A small pouch or a longer compatible cable may be useful, but verify cable requirements before substituting one.
Compatibility and formatting need care
The datasheet lists Windows 7 or later and macOS 10.12 or later, while cautioning that compatibility varies with the computer and operating system. It says reformatting for Apple's Time Machine may be required. That is a practical setup question to settle before moving a long-term backup onto the drive: confirm the intended filesystem and any data already stored, because reformatting erases existing content. The datasheet lists a three-year limited warranty for the model family, but it cannot establish warranty eligibility for a used device or an offer today. The historical title's Rescue Service phrase is not supported by the manufacturer sheet, so it is excluded from this review.
Capacity and performance are different decisions
An SSD's small body and solid-state construction make it attractive for a frequently carried work set. The 500GB capacity is not a substitute for a larger archive disk when the data collection is measured in terabytes. Likewise, a maximum transfer claim alone does not tell you sustained performance under your workload. Video editing, backup, and many-small-file transfers stress storage differently, and the product source does not publish a guaranteed result for a particular workload. Pick it because compact SSD storage at this capacity and interface fits your task; do not extrapolate from the model name to a benchmark we do not have.
Who should shortlist it
Shortlist the Expansion SSD if USB connectivity, bus power, a small body, and a 500GB work set align with your routine. It is the easiest of these three to carry according to its product dimensions, but it does not offer the 1TB capacity or Thunderbolt array layout of the LaCie, and it is not the 400GB powered 3.5-inch HDD represented by the Pushbutton Backup. None is a universal winner: choose the connection and storage role you can actually support. Before purchase, verify that a current listing is the STJD500400 500GB model and confirm any warranty and condition terms directly.
What else to compare
Before you buy
Is this a hard disk drive?
No. Seagate identifies STJD500400 as an Expansion SSD. It is a solid-state model rather than a mechanical HDD, but that distinction does not promise a particular speed or service life.
Does it work through USB 2.0?
Seagate says it is backward compatible, at USB 2.0 transfer rates; USB 3.0 is required for USB 3.0 rates. Check the port your host computer actually provides before treating the higher figure as relevant.
Can I rely on 400 MB/s?
Treat it as a listed maximum, not a measured or guaranteed speed for your computer and workload. The host, connection path, file pattern, drive condition and cable affect real performance.
Where can I check the current price?
Use the Amazon link for current offers. Check the exact model, seller, product condition, delivery, and return terms. This page does not display a live price or confirm stock.
Sources & review basis
We use the following manufacturer documentation for the product features above. Our suitability notes and buying advice are editorial judgments based on those features, not measured performance results.
- Seagate Expansion SSD datasheet ↗ — checked October 6, 2026.
- Seagate Expansion SSD datasheet ↗ — checked October 6, 2026.
- B&H exact-MFR STJD500400 listing ↗ — checked October 6, 2026.
The decision
The STJD500400 is the small, cable-connected choice here for someone who wants an external SSD with USB 3.0 and modest 500GB capacity. It is easier to carry than a powered desktop drive, but the vendor's up-to speed is not a measured result, current Amazon identity is unverified, and the limited capacity may not suit a large archive.
Is it the right fit?
Check the exact model and today’s offers on Amazon.