The MobileSTOR MS4UM+B is a compact JBOD tower utilizing the latest SATA port multiplier and USB 3.0 technology, where one single eSATA cable or USB 3.0 cable connects to four SATA hard drives. Four hard drives can be access to the computer individually, providing instant storage expansion with ease. Designed with easy installation in mind, the trayless MS4UM+B allows instant setup by simply inserting the hard drives after opening the protective ventilating cover. Both USB 3.0 and eSATA provide high performance transfer rate. USB 3.0 are now available with the various systems while older USB 2.0 port is backward compatible. Optional USB 3.0 controller card is available. Port Multiplier technology is widely available in current eSATA port, including home sever, laptop and personal computer, and an optional port multiplier supported eSATA controller can be purchases for added performance and functionality, such as RAID application. MS4UM+B supported in Windows, Linux and Mac, including storage expansion, home server applications as well as personal data backup. Four hot-swappable hard drives slots are behind the front cover to allow easy trouble shooting and hard drive replacement. The newly trayless design allow easy installation. With adjustable cooling fan design, and high performance transfer rate to support various audio and video editing problems, MS4UM+B is the ideal storage tower for high-end computing.