My Book Thunderbolt Duo dual-drive storage system delivers the optimum fusion of performance and capacity. This drive offers two Thunderbolt ports delivering the revolutionary data transfer speeds available only with Thunderbolt technology. Daisy chain multiple devices through My Book Thunderbolt Duo and enjoy nearly unlimited flexibility and performance in your creative life. This product come pre-formatted for Mac OS X Snow Leopard or Lion operating systems. Requirements: Computer with Thunderbolt connector Mac OS X 10.6.8 or higher. Box Contains 1 x My Book Thunderbolt Duo 8 TB model : ADATA XPG SX6000 Lite 512GB PCIe 3D NAND PCIe Internal Solid State Drive tag : NAS