I purchased this item a year ago. I bought two, keeping one as a spare. I've only used it a few times, and it's in beautiful condition with no stains. I occasionally checked the charging status and charged it when the light stopped working to keep it in good condition. I think one is enough, so I'm putting this up for sale. Alpha Nest 2 is an innovative product that utilizes alpha waves to improve the balance of the autonomic nervous system. It uses 10.8Hz alpha waves, which are considered beneficial for health. Wearing it provides a relaxing effect and promotes deep sleep. This product is patented and is praised for its ability to deliver noticeable effects even with short-term use. Alpha Nest 2 is a product that claims to promote mental and physical health by sending weak electrical signals (10.8Hz alpha waves) to the vagus nerve at the back of the neck, thereby regulating the balance of the autonomic nervous system. Next-generation sports necklace. Retail price: 330,000 yen.