The ThinkPad 1TB 5400rpm SATA 3.0Gb/s 9.5mm 4k Hard Drive option (0A65633) is our largest capacity hard drive provides TB capacity in a smaller form factor. This configuration consists of two 500GB platter design providing the largest capacity available in a 2.5inch drive. The advantage of this design enables the drive height to go from a larger 12.5mm drive to the current 9.5MM height enabling usage in smaller machine designs providing maximum capacity. The Advance Format or 4k sector emulates the 512 sector drives while delivering higher capacity points along with improved error correction capabilities. In addition to the advanced format, this drive features SATA 3.0Gb/s data transfer capabilities.