SilverStone RM23-502 2U dual 5.25' drive bay ATX rackmount industrial storage server chassis with USB 3.1 Gen1 interface Supports ATX power supplies of up to 180mm depth Supports 1 x 2.5' SSD and up to 5 x 3.5' HDD 5Gbps USB 3.1 Gen1 interface (downward compatible with USB 2.0 & USB 1.1) Dual 5.25' expansion bay brings flexibility in installing 5.25' devices Built-in fan bracket which supports up to three 80mm x 38mm fans Supports up to ATX (12' x 9.6') motherboard Supports 7 low profile expansion slots