The Bubble Level tool can be used to determine if a surface is flat. This can be helpful for setting up a tent or a cooking stove.
To determine if a surface is flat:
When the surface is flat, the background color of the level will change. You can adjust the threshold in 'Settings > Bubble Level > Level threshold'.
The exact angle of the surface in degrees on the X (left/right) and Y (top/bottom) axis is displayed at the top.
It is also possible to hold the device on its side to measure an angle and use the Y axis to measure the angle.