iStar E Storm E4M20 4U 20-Bay Rackmount Server Chassis with Mini SAS Backplane Case Type: 4U Rackmount Material: Handle - Aluminum; Main Chassis - Heavy-duty SGCC Cold-rolled Steel M/B Type: ATX, E-ATX, Micro-ATX, Up to 12.0 x 13.0 inch Expansion Slots: 7 Backplane: Mini SAS Backplane Case Type: 4U Rackmount Material: Handle - Aluminum; Main Chassis - Heavy-duty SGCC Cold-rolled Steel M/B Type: ATX, E-ATX, Micro-ATX, Up to 12.0 x 13.0 inch Expansion Slots: 7 Backplane: Mini SAS Backplane Front I/O Panel: 2x USB 2.0 Ports