The TowerRAID TR4UT-B is a 4-bay RAID enclosure that utilizes the widely available USB 3.0 and performance orientated eSATA to provide over 200MB/s in performance. With built-in support for RAID 0, 1, 10, 3, 5 with hot-spare support and JBOD, the TR4UT-B provides hardware RAID redundancy protection against hard drive failures. A brand new RAID mode, CLONE or N-Way Mirror, is introduced to replicate the saved data throughout each installed hard drive. The RAID engine is embedded within the enclosure, where all RAID parity calculation will be offload to the unit, instead of the controller card or computer, to achieve high performance. The unit's hardware RAID capability also helps to eliminate OS compatibility issues where installation software is unnecessary. To satisfy the need for performance hungry applications, each unit is bundled with a 2-port PCIe 2.0 x1 eSATA controller card with SATA 6.0 Gbps (6G) support (Highpoint Tech R622 Controller card). PCIe 2.0 provides twice the bandwidth of PCIe 1.0 unit, allowing over 200MB/s in performance. The unit is backward compatibility with PCIe 1.0 slots, to provide eSATA connectivity without eSATA built-in. Designed with easy installation in mind, the trayless TR4UT-B allows effortless installation by simply inserting the hard drive after opening the protective ventilating cover.