Transcend's SATA III 6Gb/s SSD220S uses the latest 3D NAND technology that features vertical, stacked expansion of storage cells. By using high-quality flash memory and enhanced firmware algorithms, the SSD220S delivers greater performance and reliability. Unlike planar NAND memory, 3D NAND flash features memory cells stacked vertically in multiple layers. 3D NAND overcomes density limitations of 2D planar NAND, and delivers a higher level of performance and endurance. Taking full advantage of the SATA III 6Gb/s interface and built-in SLC caching technology, Transcend's SSD220S achieves exceptional transfer speeds of up to 550MB/s read and 500MB/s write. Transcend's SSD220S offers great Terabytes Written (TBW) values (up to 320 TB) indicating the total amount of data you can write into the drive over its lifetime. Solid-state drives dominate the market for PC upgrades because they are faster and lighter than hard disk drives. SSDs also feature less power, create less noise when in operation, and are more shock-resistant than traditional hard drives.