This is ECG/EMG shield which allow Arduino like boards to capture both Electrocardiography and  Electromiography signals. The shield opens new possibilities to experiment with bio feedback.

When used as ECG (Electrocardiograph) you can monitor your heartbeat activity and regularity over period of time as detected by electrodes attached to skin.

When used as EMG (electromyograph ) you can monitor and evaluate the electrical activity produced by skeletal muscles. The signals can be analyzed to detect medical abnormalities, activation level, gesture position and biomechanics of human and animal movement.