- The best size to capacity ratio on the market today!

- 2200 mAh capacity offers a category-best 10 hours of constant heating power

- Bluetooth app controls the Battery Pack from any smart phone

- Merino wool helps wick moisture away from feet and promote warmth

- Surround Heating Element envelopes the toes

- Safe, stable, and reliable. Just what one would expect from HOTRONIC

- The new "Welded" wires allows for a seamless sock for a better fit with more comfort

- Material: 54% polyamide, 25% elastane, 21% wool (merino)

The Heat Sock Set XLP 1S BT Surround Comfort is the pinnacle in warmth, performance, and longevity. Combining a pair of HOTRONIC XLP 1S BT Battery Packs with the Soft Compression and Surround Heating Element of the Surround Comfort sock, and then allowing control via a Bluetooth App, HOTRONIC raises the bar with convenient Constant Heating Power when needed most - in the cold!