Thermic C-Pack 1700BT

The Therm-ic C-Pack 1700 B is a Bluetooth battery pack for Therm-ic heated insoles. It delivers up to 17 hours of warmth across three heat levels, which you can set with the rotary dial on the battery or remotely through Therm-ic's smartphone app. A USB charger is included, and a full charge takes 7 to 9 hours. Therm-ic calls it the most effective battery in its C-Pack range.

The trade-off is that this is a dedicated system. The C-Pack 1700 B works only with Therm-ic Heat Flat, Heat 3D and Heat Kit insoles, and the long charge time means plugging it in the night before a ski day.

It is built for skiers and winter athletes who struggle with cold feet and want reliable heat from first chair to last. App control lets you adjust heat without touching the battery.

Therm-ic sells this battery as a single unit, so plan on one per foot. It pairs with compatible Therm-ic heated insoles, and an AC wall charger is sold separately.

We think the C-Pack 1700 B is a great upgrade for anyone tired of cold toes. Long battery life and easy app control make it one of the best ways to stay warm all day on the hill.