The 4100 Series Hand-Held Gaussmeters are easy-to-use and ideal for commercial or home use. They accurately measures extremely low frequency magnetic fields generated by electrical equipment. Applications include detecting magnetic field emissions from a wide variety of sources including video display terminals (VDTs), AC power lines, office equipment, household appliances and all types of electrical and electronic equipment. The models 4180 and 4190 feature three axis sensors which ensure that measurements remain accurate regardless of the orientation of the instrument.