The On-Unit UI is the circular user interface located on the top of the interior portion of the unit. The On-Unit UI contains an outer ring with four buttons and a center touchscreen. The buttons include: A power button (for on/off/sleep), left & right arrow buttons (for adjusting the temperature, and accomplishing screen-specific functions), and a Home button (O) for: 1) navigating back to the Home Screen, 2) navigating from the Home Screen to the Secondary Screen.