MPC-3900 Is No Longer Available
The MPC-3900 comes with 6 drive bays that support SATA hard drives. Each SATA hard drive is installed in a removable tray.
These images show two of the removable drive bays. Unlike the drive cage that houses the other four SATA removable trays, these vertically mounted drive bays can be completely detached from the chassis. The drive bay consists of the lock/eject lever (2), removable tray (3), and the drive connectors (1) mounted on the drive cradle.