Therm-ic Heated Socks Batteries - S-Pack 4000B

The S-Pack 4000B battery pack provides up to 23 hours of heating time for compatible Therm-ic and SIDAS heated socks, with Bluetooth control through the new Therm-ic app.

With up to 23 hours of heat, the S-Pack 4000B offers the longest battery life in the current S-Pack range. It features three heat levels, allowing you to adjust the heat to suit your needs.

The batteries feature a durable splash- and dust-resistant design, while the snap fastenings ensure a secure connection to compatible Therm-ic heated socks. The USB-C charging system allows for quick and convenient charging, and the included charger allows both batteries to be charged at the same time.

What's Included:

• 2 × S-Pack 4000B rechargeable batteries
• 1 × USB-C charger for simultaneous charging

Heating Duration:

• Level 1: up to 23 hours
• Level 2: up to 10 hours
• Level 3: up to 7 hours

Features:

• Bluetooth control through the new Therm-ic app
• Three heat levels
• Up to 23 hours of heating time
• Longest battery life in the current S-Pack range
• Splash- and dust-resistant construction
• Secure snap connection to compatible heated socks
• USB-C charging
• Charges both batteries simultaneously

Therm-ic App Compatibility:

• The S-Pack 4000B is compatible with the new Therm-ic app
• For the 2026/27 season, the new Therm-ic app is compatible only with the S-Pack 3000B and S-Pack 4000B
• Previous-generation Bluetooth batteries, including all C-Pack models, continue to use the Therm-ic HC app

Compatible Heated Socks:

• The S-Pack 4000B is designed for use with Therm-ic and SIDAS heated socks featuring S.E.T. or Fusion technology
• Important: The new Ultra Warm Sensor S.E.T is only compatible with the S-Pack 3000B and S-Pack 4000B

Technical characteristics:

• Heating time: 23hr
• Colors: Black
• Connected: Yes
• Type: Batteries & heating accessories
• Activities: Ski

Therm-ic has a long history, which began with the invention of heating systems for ski boots. Building on the developments and patented technologies of the last 20 years, our range of products now includes a variety of high-quality solutions in the field of portable heating systems, which are proven to provide warmth.

Our history begins with a declaration of love - to the world's most beautiful sport: skiing.

Imagine skiing in the mountains on a beautiful blue-sky day. Fresh powder swirls around you as you make turns down an untracked slope with the sun in your face. Everything is perfect, except for one thing: Cold feet and hands that refuse to stay warm, regardless of how much you stretch them or which high-tech materials you are wearing. It is uncomfortable, annoying, painful and it ruins a perfect experience.

The founders of Therm-ic must have had very cold feet because back in the 70s, they decided to deal with the problem.

The first steps: To begin with, they developed a heating device that spread warmth via the insole to the ski boot. A great idea, however, when the external batteries became wet, they stopped working. So, the search for a better solution continued. Over time, ideas improved and so did battery technology. The next development was a heated insole that worked as a barrier to the outside environment and wouldn't allow cold air inside of the boot. This clever invention could be used in any ski boot - or everyday shoe.

The year was 1998 and Therm-ic was born.

Cold as a catalyst: The idea created the first partnerships with big ski boot brands, and our product and brand became known to more and more customers. The insoles and people's warm feet were often an issue discussed on chairlifts and gondolas - social marketing before Facebook - but we wanted more: more knowledge, more expertise and more warmth.

In cooperation with universities and research departments, we started to get closer to the issue of cold itself: How does it begin? What effects does it have on performance, safety, coordination and balance? What health problems can occur as a result? And, most importantly, how can warmth be kept inside of the body?

Therm-ic grows: We became cold experts, and our know-how was requested more and more often. Our team started talking to people around the world, convincing brands, companies and end-consumers that there was a real solution to cold feet. Under the leadership of August Stangl, who has a long history at Therm-ic, the brand grew, export started and soon products could be found in 30 countries worldwide. Furthermore, he formed partnerships with big players in the ski, snowboard and work segment.

The growth led to many things like permanent warmth for the hands and feet, insulation for the entire body and care products. In addition to products running on batteries or via Bluetooth, we created environmentally friendly, non-electronic solutions as well.

Our portfolio consists of patented products for sports and leisure as well as working shoes. Today, Therm-ic cooperates with brands such as Rossignol, Tecnica and K2 when it comes to ski boots as well as the work shoe brand Sievi.

Being cold is now a thing of the past.

Therm-ic today: Today, we are part of the SIDAS Group, which is a worldwide leader in foot comfort solutions, with specialized products like insoles, socks and foot protection. Our know-how is the perfect addition.

In 2017, we started a major relaunch, updated our design and logo and presented new products. Now, we are ready for anything that the future brings - like new product developments and partnerships.

Therm-ic is located in Voiron, in the French Alps, and we still have at least one foot in the snow - as well as our heart and brain - with our great love for skiing.