No wires or batteries needed. This water resistant foot warmer offers up to 2,500 hours of comfortable heat to cold feet. It is rechargeable and operated by a wireless remote with 3 settings; High, Medium, and No Heat. High heats up to 111 degrees Fahrenheit. The rechargeable battery is a lithium-ion polymer battery, which is embedded, in the foot warmer insole. Don't worry about the cost of charging; it comes out to .05 cents/hour! The charge lasts up to 5 hours on medium heat. The package includes 2 heated insoles with batteries, 1 remote control with battery, 1 lanyard, 1 drawstring travel bag, 1 global charger, and 1 instruction booklet.