HGST 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 Industry's leading 4TB capacity in a standard 3.5-inch form factor Industry's best Idle and Active power efficiency (Watts/TB) Reliable, field-proven, 2nd generation HelioSeal process and 7Stac design 2M hours MTBF rating & 5-year limited warranty Advanced format 4Kn and 512e models