The first time I use it, my skin will feel a little itchy, indicating that the necklace is releasing negative ions. Negative ions can promote the synthesis and storage of vitamins, strengthen and activate human physiological activities, so they are also called "air vitamins". It is considered that it, like food vitamins, has a very important influence on human body and other biological activities. For example, after a thunderstorm, negative ions in the air increase and people feel very comfortable.