The product is a set of four 12 TB Western Digital WD Caviar Blue SAS hard disk drives. They are internal desktop drives with a form factor of 3.5 inches and a rotation speed of 7200 RPM. The drives come in a color combination of silver and black, and have a storage capacity of 12 TB each. The interface supported by these drives is SAS and SATA, and they have a cache size of 8 MB. These untested drives are not sure if they work, but they are compatible with PCs and offer a high storage capacity for desktop use.