The Mobile Warming Merino 2.0 Heated Socks are a thoughtful blend of comfort and Mobile Warming's Mobile Warming technology. Powered by our Powersheer USB-C 3.7-Volt Lithium-ion battery that provides long-lasting warmth for up to 16 hours on a single charge. Take all-day comfort to the next level. Whether you're in deep back country powder or an early morning job site, keep your feet warm and improve circulation to avoid stiffness, muscle fatigue, and soreness. With heavy cushioning in key areas and heating elements under the front of the foot, you can avoid the discomfort and numbness that come with being outside in cold conditions. The Merino Wool fabric blend is breathable, and the full-calf length provides comprehensive coverage. Use our simple 4-button remote control to adjust your heat settings, ensuring you maintain complete comfort and control. Features: Compact, Comfortable 3.7 volt Rechargeable Lithium-Ion Battery USB Charging Compatible (use any universal wall adapter you already own to charge) Up to 16 Hours of Heat Per Charge On Lowest Heat Setting Hidden Wires, Calf Contoured Battery, and Low Profile Heat Panels Improved wire channel to keep internal wire in place Merino Wool Fabric Blend Sock Content: 54% Merino Wool, 37% Nylon, 6.6% Polyester, 2.4% Elastane (Lycra) Moisture-Wicking Fabric 4 Selectable Heat Settings Integrated Battery Compartment Over-the-Calf Height Improved stretch at top of sock