The new S Series are Hotronic's most powerful-yet-compact Battery Packs.
With enhanced reliability and longevity, the new s Series batteries maintain 55% of a full charge and 95% of their initial capacity after four years of nonuse! Plus, an increase in capacity offers up to a combined 30% in higher average temperatures over "e" and "m" batteries series on the same settings. Longer durations on a single full charge, all when needed most, in the cold!
If you currently have the older version of the Hotronic FootWarmers you'll want to take advantage of the longest battery performance and better charging by buying two new Power Plus S3 battery packs and the S/e/m series recharger. Use your current insoles with heat elements and save over the price of a new set of FootWarmers.