A Holter Monitor is a small portable device that continuously records your heart’s activities. It has wires with electrodes that are attached to the skin. It is like an extended version of ECG and detects anomalies in the heart rhythm. It is battery operated and wearing it is not painful.
If you have a hairy chest, you might need to shave it to attach the electrodes properly. You have to carry the monitor in a pouch or your pocket. Don’t bath while wearing the monitor. Also, avoid X-rays, metal detectors and high voltage areas.