Magnetic flux density B a measure of magnetic field strength is the amount of magnetic flux through a unit area taken perpendicular to the direction of the magnetic flux. It can be described in terms of a vector field. Fluxgate sensors can determine magnitude and direction of B. Using MAGNETOSCOP and MAGNETOMAT magnetometer with appropriate sensors, magnetic flux density can be determined simultaneously in 1 up to 3 directions. By means of a differential probe the magnetic flux density gradient can be determined in one direction.