Smart Space Saver: Hot-Swap supported HDD cage converts space of 3x 5.25' CD-ROM / DVD-ROM to 4x 3.5' or 2.5' SATA I, SATA II, SATA III, or SAS HDD tray. Reliable Cooling: Engineered with optimal cooling in mind. A single rear 120mm exhaust fan produces effective airflow and cooling. Rugged Design: Made of durable steel and ABS materials to ensure years of reliable use. Compatible with Rosewill model L4000U / L4500U / R4000U RSV-SATA-Cage-34 support SAS 6Gbps only.