Utilizing our new Powersheer Micro 3.7-Volt Lithium-Ion battery, our new Thermal Heated Socks provide long-lasting warmth for up to 10 hours on a single charge. Our Thermal Heated Socks are a thoughtful blend of comfort, cost, 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. Our Thermal 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 cotton/poly blend is breathable, and the calf length provides full coverage.Sock Features:90.6% Polyester, 8.3% nylon, 1.1% spandexCotton/Poly/Other blendCalf LengthComfort ToeHeavy Cushioning in Key AreasHeat Under Toes OnlyNew Powersheer Micro 3.7v BatteryUp to 8 Hours of HeatUniversal USB Charging InputBattery Features:Powersheer Mini Rechargeable Lithium-Ion Battery (3.7V 2200mAh)Up to 11 Hours of Power Per ChargeUL/CE certifiedBattery size: 8in x 1.1in x 0.8in2.8in x 1.1in x 0.8inAC wall charger includedCharge Time 3-4 hoursIncludes:(1) Pair Standard Heated Socks(2) Powersheer Mini Rechargeable Lithium-Ion Battery (3.7V 2200mAh)(1) AC Dual ChargerKeep your feet warm and avoid discomfort, numbness, and poor circulation in your extremities with Fieldsheer's Thermal Heated Socks. Powered by a robust Powersheer Micro 3.7-Volt Lithium-Ion battery that provides long-lasting warmth for up to 10 hours on a single charge. Our tri-blend materials are odor-resistant and wick moisture away from the skin to keep you comfortable all day, no matter how harsh the conditions. Since 1978 Fieldsheer has been designing and manufacturing rugged, performance-driven gear for avid outdoor enthusiasts, motorcyclists, workers, and more. Whether you're in deep backcountry powder or an early morning job site, you can trust our Thermal Heated Socks to provide powerful warmth instantly. With a focused heat zone under the toes and 3 distinct heat settings and long fit for coverage above most boots, Fieldsheer's Thermal Heated Socks will become an essential part of your winter gear.The internal heating elements are slim and go unnoticed with heavy cushioning in key areas and a comfortable toe. With a universal USB charging input and a 3-4 hours charge time*, operation is seamless and easy. Perfect for use with any work boot, snowboard or ski shoe, or running shoe, the Thermal Heated sock is ideal for construction sites, the slopes, or early spring jogs. Powered by our Mobile Warming Technology you can get the job done and stay in the field longer with Fieldsheer's Thermal Heated Socks. Keep at it all day with Fieldsheer's powerful heating technology combined with the highest quality materials and thoughtfully designed to keep you warm, dry, and comfortable for hours without forfeiting range of motion, style, or performance. The integrated battery compartment conveniently keeps the power block in a comfortable position throughout the day, with no need to adjust or worry about them shifting. The perfect blend of high-performance materials and technology to make sure you stay warm, dry, and comfortable no matter what the weather throws at you.Don't let cold weather or harsh conditions cut your day on the slopes short or force yourself to work in uncomfortable boots with frozen feet and poor circulation; choose Fieldsheer's Thermal Heated Socks and get to the finish line. Fieldsheer's heated socks are designed for every cold climate, from arid high-deserts to Alpine forests and wherever your adventure takes you. These aren't an accessory they are a necessity if you're going to enjoy time in the snow or work outside in cold conditions.Replacement batteries:Battery SKU: MWCB37V42 - 3.7V Powersheer Micro Dual Battery Pack NW (3.7v 2200mAh) Mobile Warming Unisex Thermal 2.0 Heated Socks