Thermacell heated insoles use rechargeable batteries to keep your feet warm for up to five hours at a stretch. A wireless remote lets you adjust the temperature—without taking off your boots—to one of three settings: off, medium (100°F), and high (111°F). Lithium-ion batteries are housed in the insoles, so there are no external battery packs or wires. Recharge time is about four hours. Insoles can be customized for shoe sizes from a woman’s 4.5 to a man’s 14. Standard insoles are available online for $130; the Proflex model, which offers removable batteries and the option of USB recharging, is $180. Schawbel Technologies, 866.753.3837, thermacell.com