The IW-R200N-CR550 is a 2U rackmount enclosure that supports an ATX or CEB motherboard. It supports up to 6 internal 3.5" and 2 external 5.25" drive bays. It features support for up to 7 low profile pci expansion slots or 3 full height pci expasions. Includes 550W Redundant 80+ Platinum power supply.