The front of the WiebeTech RTX220-QR features a status display and numerous LEDs to let you know that everything's OK... or not. The white buttons are used to change from RAID 0 to RAID 1 or vice-versa, and to look at the drive temperatures.
Here one of the drive bays is open. As with the Drobo products, you don't need a special tray - you just push a bare drive into the bay and close the door. There are cylinder locks for keeping the drive bays shut.