Super low power flux-gate magnetometer LEMI-031 is intended for the monitoring of three components of the magnetic field vector and its variations in land and laboratory conditions. The instrument is specially designed for battery powered applications and has differential outputs for easy coupling with analogue to digital converter. Several know-hows are used to keep the power consumption of LEMI-031 magnetometer at world lowest level. The current version of the instrument is destined to be embedded into a host system. The electronic board could also be packed in the body for autonomous applications.