Seagate Momentus 5400 640 GB 5400RPM SATA 3Gb/s 8MB Cache 2.5 Inch Internal Bare Drive ST9640320AS 640GB Capacity and 8-MB Cache Seagate SmartAlign technology provides a transition to 4K sectors without the need for software utilities. Seagate G-Force Protection technology can detect when your laptop is in a free-fall, swing the drive heads to a safe zone and keep the data safe. Best-Fit Applications include mainstream and high-performance laptops, external storage solutions, boxes, Industrial applications requiring a small form factor Industrial applications requiring a small form factor. Two Year Warranty