This 4 x 3.5 in. Hotswap miniSAS Tower is an external 4-bay trayless SASSATA disk array storage tower. It provides users a most big storage capacity for up to 4 hard drives for RAID configurations. This external tower is designed with one high quality connector. Ball bearing 80 mm. cooling fans offer long lasting and enhanced thermal cooling solution.Features. Supports 15x SASSATA 3Gbs Hard Drives. 3x eSATA Connectors with Port Multiplier Support. 120 mm. Cooling Fan for Ventilation. LED Indicators for Power and Activity on Each Hard Drive. Trayless Design. Hot-swappable Both on Host and DeviceSpecification. RoHS Compliance Version - Yes. Form Factor - 4U. Host Interface - 3x eSATA-Port Multiplier. HDD Interface - 3.5 in. SAS SATA III. Hotswap 3.5 in. - 15. LED Display - Power and HDD Activity. Material - Chassis 1.2 mm. SECC Zinc-Coated Steel. Main Color - Black. Power Supply - 750W Single PSU. Raid Level - Configured by Host Controller. Cooling Fan - 1 x 120 mm.. Dimension - 25 x 22 x 12 in.