The Therm-ic SuperMax was discontinued by Therm-ic in 2017. In 2018, Therm-ic updated all insoles and batteries. You may need to update to the current C-Pack versions.
You can see our current selection of Therm-ic boot heaters.
The Therm-ic SuperMax Powerpack
had a global battery charger to be used in Europe and offered battery overcharge protection. This is a big advantage, over charging can damage your batteries and cut down on their life expectancy. The SuperMax are for use in boots with pre-wired Therm-ic heating systems and the two batteries would last up to 18 hours on a low setting.