1.Optional fans on rear window. 2.Easy-swap front fan w-removable fan filter. 3.Two-way usage for rackmount and stand -alone,Optional 22inch mounting rail or top cover and foot stand for stand-alone. 4. 2xFront USB 2.0 ports. 5.Chassis intrusion switch. 6.Metal front door w/key lock. 7.Reset switch to disable audible warning.8.Rotate-able device cage for rackmount and stand-alone. 9.Removable fan filter.10.Up to 2pcs of card-retainer to avoid the vibration of add-on cards. 11.Device brackets with rubber for anti-vibration. 12.Optional mounting plate. 13.Changeable optional slot bracket - Optional 7 slot bracket with SCSI ports or 15 slot bracket for backplane.