Stay warm on the trail with the thermotrek hand warmer. The 4400 mah lithium Ion battery provides up to an impressive 6 hours of continuous heat on a full charge. Thermotrek heats up quickly and reaches a maximum temperature of 113 degrees Fahrenheit (45 degrees Celsius). unlike chemical hand warmers, thermotrek can be recharged multiple times. Just plug it into the USB port on your pc or a compatible AC charger using the included cable. The rugged aluminum construction and protective silicone caps make thermotrek perfect for cold weather excursions like cross-country skiing and mountaineering.