HGST MegaScale DC 4000.B HMS5C4040BLE640 (0F23139) 4TB Coolspin 64MB Cache SATA III 6.0Gb/s 3.5" Enterprise NAS Hard Drive - w/3 Year Warranty - Walmart.com
Amazon.com: HGST Ultrastar 3.5-Inch 4TB 7200RPM SATA III 6Gbps 64MB Cache Enterprise Hard Drive with 24x7 Duty Cycle (0F14683) : Electronics
HDN726040ALE614 HGST Hitachi Deskstar NAS 4TB 7200RPM SATA 6Gbps 128MB Cache 3.5-inch Internal Hard Drive
Hitachi HGST 4TB SATA 3.5" 7200 RPM 6Gb/s 0F14683 Internal Hard Drive HDD | eBay