External storage systems with an eSATA interface offer great flexibility. Single drive enclosures are great for solid state drives (SSDs) or hard drives. Many enclosures include swappable drive trays, which are perfect for managing daily backups and multiple projects, and most are portable. Some enclosures, like Sonnet's Fusion D400QR5 and Fusion F3, feature hardware RAID controllers that enable up to four drives to communicate with the host adapter through one cable. Through its two ports, Tempo SATA 6Gb/s PCIe 2.0 can handle up to eight drives.