Thermic S-PACK 4000B

Skiers who need the most run time from their heated socks should look at the Thermic S-PACK 4000B, a high-capacity rechargeable battery set with Bluetooth control. Three adjustable heat levels and USB-C charging keep it simple, and it offers the longest battery life in Therm-ic's current S-Pack range. That means steady, warm toes from the morning lift line to après.

Why we like it:

On its lowest setting it runs nearly a full day and night, so cold-footed skiers can stop rationing heat by midafternoon.

Features and Functions:

Run time is the headline here: up to 23 hours on level one, 10 hours on level two and 7 hours on level three. Two batteries and a USB-C charger that powers both at once come in the box, and the Therm-ic app lets you change heat levels from your phone. Splash and dust resistant housings and snap fastenings keep the packs secure, and they're designed for Therm-ic and Sidas heated socks with S.E.T. or Fusion technology, including the Ultra Warm Sensor S.E.T. socks.

Bottom Line:

The pick for skiers with chronically cold feet or long days outside who want maximum warmth from compatible heated socks.