The ColdSky Hand Warmers Rechargeable 2 Pack are portable, magnetic electric devicesdesigned to keep your hands warm during cold conditions. Each hand warmer features a rechargeable 2000mAh lithium-ion battery that fully charges in about 3 hours, providing between5 and 16 hours of heat depending on the setting. They offer three adjustable heating levels—low, medium, and high—allowing you to customize warmth based on your preference.