RM-3155 has a unique space-saving design. It is a 3U chassis with a 4U capacity. It can support different version of AT, Micro ATX and ATX M/B (up to 12" x 13 "). Whether it is used as a web server or high performance computing or database server, this chassis provides ample storage space and cooling. Its 7 PCI slots support PCI, PCI 64bits, AGP, and PCI-Express add-on cards which enable expansion and upgrades for specialized functions and tasks.