Instant Readings Give The First Readout After Four Heartbeats

This monitor can be used any time, even during exercise and is an excellent tool for studying trends, irregularities, or even learning biofeedback. It is so easy to use that all you need to do is grasp the rings and it turns on. When you let go, it turns off. The crystal controlled accuracy never needs calibration and features a range of 30–240 bpm. It comes in a water-tight casing and includes a 9 V alkaline (transistor) battery and instructions.