The SATSASTRAYBK Hot Swap Hard Drive Tray is specially designed as a spare/extra 2.5in/3.5in SATA/SAS Hard Drive Tray for the SATSASBAY3BK (3 Drive Hot Swap SAS SATA Backplane) allowing you to use extra spare/replacement hard drives in addition to what is installed in the backplane/mobile rack. This extra hard drive tray features an upgraded design with additional air vents and specially designed vibration dampening springs, providing the ideal replacement for misplaced trays or a convenient solution for having extra hard drives available for your storage solution.