evidence: The zapper works amazingly to kill microbes such as bacteria, protozoa, fungi, and possibly even virus in water. Since the human body is mostly water, it would make sense that it would have possible positive effects. Our zappers range in price from about $109.00 to over $500.00, depending on the model and features. If you can not afford one, simply try battery tapping. While it is only about one tenth as effective as the best zappers, it can stop a cold or flu in its tracks but may not be as effective on other problems. To try battery tapping, simply wet the index fingers of both hands. Place the index finger of the left hand on one battery terminal and tap the other terminal as fast as you can with the right index finger ( the hands should not touch each other at any time ) for 7 minutes or longer. After the 7 minute or longer time, stop and rest for 20 minutes. Repeat the tapping for the same amount of time that you did the first time, stop and rest for another 20 minutes. Then repeat for at least a third time and if possible, a fourth time.