PERFECT GIFT - It's a MUST HAVE to spend a cold winter, especially for Raynaud's arthritis sufferers for heat therapy needs. Large battery capacity - 5200 mAh lithium rechargeable battery with USB-C charging port ensures a long using time. It can also be used as a power bank to charge your electronic device at any Time. Fast heating & 3 levels - press the switch and instantly release the warmth for you. Hand warmers can rapidly warm up double sides in seconds. 3 levels of temperatures 95-107°f/104-118°f/118-131°f at your choice. Upgraded security - The optimized and upgraded Circuit ensures its long lifetime, providing protection against over discharging, over charging, overheat, and short circuit. Exquisite comfort - Made of high-tech aircraft-grade aluminium and ABS material, thousands of polished exterior Material, Smooth and warm, portable and compact as well anti-skid in one hand.hand warmers