Electromyography (EMG) is a diagnostic procedure to assess the health of muscles and the nerve cells that control them (motor neurons). Motor neurons transmit electrical signals that cause muscles to contract. An EMG translates these signals into graphs, sounds or numerical values that a specialist interprets

These are very cool prototype looking devices. They each come with respective sensors headband monitor and finger monitor. Marked Behavioral Instruments on each device and units measure 6" x 4" x 3". Operates on 9 volt that is accessible in the back panel.