2.5-inch SATA SSD
Direct Answer
The 2.5-inch SATA SSD shares its physical footprint (100mm x 70mm) with laptop hard drives, making it a drop-in upgrade. SATA III limits it to a real-world maximum around 550-600 MB/s regardless of how fast the drive's flash memory could otherwise go.
Source: SATA-IO
Specs
| Dimensions | 100.2 x 69.85mm (7mm or 9.5mm height) |
| Interface | SATA III (6 Gbit/s) |
| Usable Max Throughput | ~600 (after protocol overhead) MB/s |
Built to Replace a Hard Drive
The 2.5-inch SSD deliberately shares its physical envelope and SATA connector with 2.5-inch laptop hard drives, which is what made it the easiest possible upgrade path when SSDs first went mainstream -- swap the old drive out, put the new one in, no other changes needed. Drive height varies: 7mm is standard for most modern SSDs, while some older or specialty drives use a 9.5mm case to match older, thicker hard drive bays.
The SATA III interface itself is the form factor's real bottleneck today: its 6 Gbit/s signaling rate works out to about 600 MB/s of usable throughput after protocol overhead, a limit modern flash memory and even budget NVMe drives can exceed several times over. That ceiling is why 2.5-inch SATA has become the budget/legacy option rather than the performance choice, even though the drives themselves remain reliable and inexpensive.