The MC858 Extremely Low Frequency (ELF) sensor has maximum response near 58 Hz, which provides a strong output at 50 Hz and 60 Hz. It is used, for example, for measuring fields from building wiring, power lines, and equipment powered at 50 or 60 Hz. Display instrument resolution of 0.1 mV AC or better is recommended for most applications. 

Each sensor is tested using NIST traceable methods and instruments.  Calibrated to ANSI Standard 644-1987.  Certificate included.