Connect and hot swap four 3.5in SATA III or SAS II hard drives to your computer system in three 5.25" bays, with support for SATA 6 Gbps Compatible with Servers & Desktop computers with 3 available 5.25in bays and SATA or SAS hard drives Trayless SATA Backplane / Hot Swap Bay / Backplane / Mobile Rack / SATA 6 Gbps / Key Lock / 70mm Fan Onsite data backup as a secure alternative to cloud storage Add a hot-swap bay to a server or workstation computer that you can use as a removable backup