20x hot-swappable SATA (I or II) / SAS drive bays Supports up to twenty 3.5" SATA (I or II) or SAS disk drives; * 1 x slim CD-ROM bay,1 x FDD bay, 20 x 3.5 " hot-swappable drive bays , 1 x HDD bay Hot-swappable HDD tray with special designed power-off and lock mechanism. * Support EEB (12"x13"), CEB(12"x10.5"), ATX (12"x9.6"), Micro ATX (9.6" x 9.6") motherboard, Screwless top cover * Seven ball bearing fans for better ventilation 5 x 80mm middle fans, 2 x 80mm rear fans Switch:Power ON/OFF x 1, System reset x 1 Indicator:Power ON/OFF x 1, HDD x 1, NETWORK X 2 * Power Supply Options:Standard ATX, mini redundant power supply Dimensions ( W x D x H ):19" x 25.5" x 7 " (483mm x 650mm x 176mm)Packing:Double boxes