The battery used in these insoles is rechargeable, and can be used for up to 4.5 hours, depending on the temperature setting. This time can be further increased by only switching the insoles on for short bursts as needed. The cable plugs into a convenient micro-USB port in the side of the heel, so there is no need to remove the battery in order to charge.
The insoles also come with a USB cable which can be used for both insoles at the same time, using any existing USB wall plug, PC or Laptop. You can even charge these insoles on the move with any other micro-USB car charger or battery powered micro-USB charger pack.