Synology 4TB/3.5"/7200RPM/256 MiB/6Gb/s, Enterprise-Grade SATA HDD designed for Synology NAS (HAT5320-4T)

-Capacity: 4TB
-Form factor: 3.5"
-Interface: SATA 6 Gb/s
-Rotational speed: 7,200 rpm
-Buffer size: 256 MiB
-Mean Time Between Failure (MTBF)3: 2,000,000 hours
-Warranty 5 years