The Pro merino wool heated socks powered by the Powersheer® Micro 3.7-volt lithium-ion battery that provides long-lasting warmth for up to 8 hours on a single charge. Pro merino wool heated socks are a thoughtful blend of comfort and Fieldsheer’s® Mobile Warming® Technology. Since 1978 Fieldsheer has been designing and manufacturing rugged, performance-driven gear for avid outdoor enthusiasts, motorcyclists, workers, and more. The Pro merino wool heated socks take all-day comfort to the next level. Whether you’re in deep backcountry 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 blend is breathable, and the mid-calf length provides comprehensive coverage. The included wireless controller makes toggling between 3 heat settings effortless, making sure you maintain complete comfort.