This lot includes two 640GB Western Digital WD Blue desktop hard drives with SATA II interface. These hard drives have a rotation speed of 7200RPM and a cache of 16MB. They are compatible with HDD drive types and have a 3.5-inch form factor. The model number is WD6400AAKS and the brand is Western Digital. Please note that this product contains a chemical that is known to the State of California to cause cancer, as indicated by the California Prop 65 Warning. This lot of hard drives is ideal for enterprise use and offers a storage capacity of 640GB each. They are in great working condition and have been fully tested.