3 x 5.25-Inch to 4 x 3.5-Inch SAS/SATA 6.0 Gb/s Trayless Hot-Swap Cage Aluminum frame, light weight and durability design Tray-less and Screw-less HDD mounting Aluminum front bezel with metal key lock mechanism for security Integrative shaping aluminum design for quickest heat sink Supports Hot-swap & RAID configuration (additional RAID controller needed)