Basix + Powerpacks can be used with regular rechargable or non-rechargable AA batteries. Basix + The heating capacity depends on the battery selection. Based on the use of the patented impulse control system, Therm-ic boot heating systems not only generate comfortable, but also healthy warmth because they naturally stimulate the blood circulation at the same time The heat can easily be adjusted by means of three selectable temperature levels, simply by pushing the + or - button and is indicated via 3 LED lamps. Basix + powerpacks are compatable with any Therm-ic heatable insole and Therm-ic pre-wired system. Therm-ic recommends rechargable batteries for the use of the Thermic Basic Battery Charger. Package contents: + 2 Basic + Powerpack housings with integrated heat level switches (batteries not includes in the package) (BATTERIES NOT INCLUDED) (INSOLES NOT INCLUDED)