WD Red Plus WD40EFPX - hard drive - 4 TB - SATA 6Gb/s
WD Red Pro 4TB NAS Hard Disk Drive - 7200 RPM SATA 6 Gb/s 64MB Cache 3.5 Inch - WD4001FFSX,Amazon.com: Western Digital 4TB WD Red NAS Internal Hard Drive HDD - 5400 RPM, SATA 6 Gb/s, SMR, 256MB Cache, 3.5,WD Red Plus WD40EFPX - hard drive - 4 TB - SATA 6Gb/s,Amazon.com: Western Digital 4TB WD Red Plus NAS Internal Hard Drive HDD - 5400 RPM, SATA 6 Gb/s, CMR, 128 MB Cache, 3.5