The Western Digital 640GB 7200RPM SATA 3.5" HDD WD6400AAKS-40H2B0 655-1528A is an internal desktop drive with a storage capacity of 640GB. It features a SATA interface and a rotation speed of 7200RPM, providing fast data access and transfer. The drive is designed in a 3.5-inch form factor and has a cache size of 16 MB, making it suitable for high-performance computing tasks. Made by Western Digital in Thailand, this HDD model is a reliable choice for storing and accessing large amounts of data in a desktop environment.