I understand they have to emit a very specific frequency to help you. They emit red light and infrared. You can use both simultaneously or either. Mine is prescribed for a 20 minutes in the morning and 20 minutes in the evening. They come in various sizes and various features such as built rimers. I think mine is helpful and actually has helped reverse some of the symptoms, I use mine in addition to some pills to treat neuropathy and maintain good health such as recommended vitamins and minerals.