Radio frequency sources include portable wireless devices such as cell phones, tablets, and laptop computers, FM/AM radios, and older televisions that operate at lower radio frequencies than cell phones. ELF-EMF sources, which have lower energy than radio frequency sources, include power lines, electrical cables and household appliances. Overdose of radiation taken to the whole body in a short time causes so much damage to the internal organs and tissues of the body that vital systems do not work. Acute health effects such as nausea, vomiting, skin and deep tissue burns, and deterioration of the body's ability to fight infection can occur within hours, days, or weeks. These effects are called deterministic' effects and are not observed at doses below certain thresholds. Positively charged radiation is harmful to our body. Negative ions can neutralize positive ions and neutralize positive static electricity. In addition, negative ions can act on the human body, improve immunity and reduce the damage of radiation to the human body. For this reason, negative ions have a more positive importance in solving the damage caused by radiation pollution to the human body. Volvox EMF Radiation Protection Necklace! OUR GUARANTEE We are confident that we offer some of the best products on the market. Therefore, we provide a 30-day guarantee. We will make every effort to ensure that you are completely satisfied with your purchase. Online shopping can seem daunting. We want you to know that there is absolutely zero risk of purchasing something. We won't make it difficult if you don't love it. We offer email and ticket support 24 hours a day, 7 days a week. If you require assistance, please contact us. Please contact customer service if you have any problems with your purchase.