Amazon.com: HGST Ultrastar 7K4000 4 TB 3.5" 7200 RPM SATA Internal Enterprise Hard Drive 64 MB Buffer 6.0Gb/s - HUS724040ALA640 / 0F14688 64 MB Cache 3.5-Inch Internal Bare or OEM Drives 0F14688 : Electronics
Amazon.com: Seagate 4TB Enterprise Capacity HDD 7200RPM SATA 6Gbps 128 MB Cache Internal Bare Drive (ST4000NM0033) (Renewed) : Electronics
HP - Smart Buy - 4 TB - SATA 6Gb/s - 7200 rpm - Hard drive
Amazon.com: Seagate 4TB 7200RPM HDD : Electronics
WD Black Performance 4TB 7200 RPM SATA III 6Gb/s 3.5" Internal CMR Hard Drive - Micro Center
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Amazon.com: HP 695842-001 4TB SAS Hard Drive Disk (HDD) - 7,200 RPM, 3.5-inch form factor, SmartDrive Carier (SC), Midline (MDL), 6Gb per second Transfer Rate (TR) : Electronics
HGST HUS726T4TALE6L4 Ultrastar 4TB 7200 RPM 512e SATA 6Gb/s 3.5-Inch Internal Hard Disk Drive
04NDPW Dell 4TB 7200RPM SAS 12Gbps Nearline Hot Swap (512n) 3.5-inch Internal Hard Drive