• 4U rackmount design
• 20x hot-swappable SATA (II or III) / SAS 6G drive bays, two 2.5" OS drive brackets.
• Five internal SFF-8087 Mini SAS connectors support up to twenty 3.5" or 2.5" SATA (II or III) or SAS hard drives;
• Backplanes are horizontal mounted for better ventilation;
• 1 x slim CD-ROM bay,20 x 3.5 " hot-swappable drive bays, 2 x 2.5" OS drive brackets;
• Six ball-bearing cooling fans for better ventilation
• RoHS Compliant;
• Redundant 4pin molex PSU connectors support redundant power supply
• Support EEB (12"x13"), CEB(12"x10.5"), ATX (12"x9.6"), Micro ATX (9.6" x 9.6"), ITX (6.7" x 6.7") motherboard
• LED indicators for power and activity on each HDD tray
• Smooth border prevent lacerating your skin
• 4pin Molex Power Adapter Option (not included): Sata power to 4pin molex power adapter

Specifications: 

Drive Bay: 20 x hot-swappable SATA (II or III) / SAS 6G drive bays, 1 x slim CD-ROM bay, 2 x 2.5" OS drive brackets. 
Cooling Fan: 4 x 80mm middle fans wall, 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 
Connector:Two front accessible USB ports, five internal SFF-8087 Mini SAS connectors, ten 4-pin molex redundant power connectors
Motherboard Compatibility: Support EEB (12"x13"), CEB(12"x10.5"), ATX (12"x9.6"), Micro ATX (9.6" x 9.6"), ITX (6.7" x 6.7")
Power Supply Options: Standard ATX power supply, mini redundant power supply (H x W: 5.91" X 3.39")
Dimensions ( W x D x H ): 19" x 25.5" x 7.0" (483mm x 650mm x 176mm)
Packing:Double boxes
Weight (without hard drive): 18 kg/39.7 lb (NET) 21.2 kg/46.7 lb (GROSS) 
Environment Temperature:0/40 °C, 32/104 °F (Operating) -20/60 °C, -4/140 °F (Non-Operating) 
Relative Humidity: 5% to 95%,non-condensing