The TowerRAID TR4M-B is a compact RAID tower utilizing the latest SATA II port feature, where one single eSATA cable connects to four 3Gpps SATA II hard drives. Designed with easy installation in mind, the trayless TR4M-B allows instant installation by simply inserting the hard drives after opening the protective ventilating cover. It supports JBOD and Spanning modes for instant storage expansion. It also supports RAID 0, 1 0+1, 5, 5+spare via included software utility, for high performance and hard drive redundancy. The package includes a 2-port eSATA PCIe card at no additional cost, which allows the connection between two TR4M units (up to 8 hard drives) using only two cables. PCI/PCI-X options are also available.