This rechargeable hot water bag takes 8-15 minutes to finish heating. Keep warm for 2-8hrs (influenced by the ambient temperature). It is sold without water, use the funnel to inject 1000ml-1200ml. It is ideal for warming hands, feet, stomach, back or bed in cold winter. In addition, it can be used as a heating pad to relieve pain, sore muscles, stiff necks and dysmenorrhea. You can use it as a small pillow for a nap at the office. It is built-in auto shut-off device to prevent overheating. The fabric is made of skin-friendly fleece, and the lining is padded with cotton to give you a feeling of softness and comfort. The inner layer is made of 6 layers of PVC material, which is to provide you with excellent insulation for a long time.