exo² products (except the StormShield Gloves) can be heated by lithium-ion batteries (Power Packs), similar to those found in today’s mobile phones. Our Power Packs are sealed, CE certified and will keep you warm for hours on a single charge.  Plus, they are completely rechargeable for use, time after time.  exo² Power Packs are lightweight and compact, so you feel the heat, not the power source.  Be sure to order your charger unit and the power cord made specially for your country’s electrical outlet configuration.  Batteries should supply 3-4 hours of continuous heat in average conditions.