1U, Optimized for WIO (W series) motherboards, 4 x 3.5" hot-swap SAS/SATA, SAS or enterprise SATA HDD only recommended, 1U 4-Port 12Gbps Backplane Support 4x3.5, 1U Redundant 700/750W Single Output Power Supply Platinum level, 54.5mm width, 2 full-height & full-length expansion slot(s) , 1 low-profile expansion slot(s), 4 x 40x56mm counter-rotation PWM fan(s)