Seagate ST4000VN006, 5,400RPM, SATA III 6Gb/s, 3.5in, 4TB capacity, AgileArray, 256MB cache, Tough, ready, and scalable. IronWolf drives are NAS-optimized for 24x7 in NAS enclosures. Tuned with AgileArray and multi-user technology, IronWolf allows you to do more with your NAS.