Hot Rox Electronic Hand Warmer &ndash; Rechargeable Hand Warmer with Two Heat Settings - Perfect for Winter Outdoor Activities such as Skiing, Hunting, Hockey, Ice Skating, Snowboarding and Hiking Heats Up Fast. HotRox hand warmers feature a specially designed heatplate that reaches the selected heat level in about 15 seconds from the moment the hand warmer is switched on, delivering heat-on-demand. When turned off, the unit cools down quickly. Runs up to Six Hours. The units rechargeable lithium battery provides power for up to six hours when hand warmer is run at the lower (Medium) heat setting, and for up to three hours at the High setting. Therapeutic. Hot Rox hand warmers are recommended by Raynauds Scleroderma Association as a source of relief from Raynauds disease, disorder that reduces blood flow in the extremities when exposed to cold and causes pain, numbness, throbbing and tingling Easy to Recharge. This hand warmers lithium battery can be fully recharged in about two hours by plugging it into the USB port of any computer. When in use it can last 3-4 hours on High setting and 5-6 hours on Medium setting Comfortable and Portable.