For PARTS ONLY NO WORKING This product consists of two Western Digital 4TB SATA 3.5 inch HDDs, specifically the WD DC HC310 and WD4000FYYZ models. These internal desktop drives have a rotation speed of 7200 RPM and a storage capacity of 4TB each. They are designed for use with PCs and feature a hot swap capability. These drives are part of the Ultrastar product line and have a cache size of 256 MB. Made in Thailand, these HDDs offer reliable storage solutions for desktop computers.