Keeps body and hands warm: Qualified carbon fiber heating elements with 3 heating levels produce consistent heat to 4 core body areas including neck, back, abdomen and waist to help keep the body warm. Long-lasting use : 10000mah power bank provides on average up to 8 to 10 hours of warmth (duration may vary with different types of power banks); our product does not include power banks. Overheating Protection: If for any reason the internal temperature of the heated area exceeds 150f, the implanted sensor will be triggered to immediately terminate the heating. "All our products have undergone strict quality inspection. If there is any quality problem or you are not satisfied with using the product contact us. We will provide you with the best solution.