Use to monitor and compare pulse rates under various exercise and rest conditions. Additionally, the sensor can show changes of blood volume/flow in the finger or ear lobe with time. the sensor has two modes of operation: measuring the BPM (beats per minute) of the heart rate or displaying the analog arbitrary value of the measured signal. Both electrodes are plethysmograph-based. The sensors consist of an infrared LED transmitter and a matched infrared phototransistor receiver. For best results, the sensor should be kept away from direct sunlight and high-intensity lights. The student whose pulse is being measured should be still without moving as much as possible. The wireless or USB module is required to operate any of the sensors. The rechargeable battery module should be used with the wireless module.