The TerraMaster F4-421 does four SATA bays and nothing else

No M.2 slots, no NVMe cache, no expansion — the F4-421 is pure 4-bay SATA storage. It accepts 3.5-inch and 2.5-inch HDDs and SSDs in all four bays. If your workload fits on a straightforward SATA array, this TerraMaster delivers without complications.