These are two 5.25" full-height extended length bays for support of two full-height devices or four half-height devices.The power connectors on the NetMEDIA Storage Expansion Unit EL are the standard IEC 320-C13 (10 amps) connectors. Suitable for two full-high devices or four half-high devices, they feature two independent power supplies, an external .8mm VHDCI connector, an internal Single-Ended Fast Wide SCSI-2 operation. They provide support for both Single-Ended SCSI or Low Voltage Differential SCSI controllers and are upgradeable to dual independent SCSI channels with optional adapter card. They also provide support for tape array or mirroring with optional adapter card and support Advanced System Management functions with an optional adapter card.