In addition, the app includes true and magnetic north headings, a magnetic strength meter, a slope level meter ... true heading, magnetic field, location, and address, plus the “course scale ...

The excited electrons interact with the Earth's magnetic field and emit red light, and he amount of red light indicates the strength and orientation of the magnetic field at that location.

Some of the properties are mentioned here: Magnetic field strength, or magnetic flux density, is a critical parameter in physics and engineering, quantified by units such as Tesla (T) and Gauss (G).