3 Temperature Adjustable Heated Socks:3.7V heated socks include a pair of 2200mAh battery.Electric heated socks have 3 step temperature settings.High(Red light),working 3-3.5Hours,Middle(White light),working 4.5-5 Hours,Low(Blue light),working 6-6.5 Hours.The heated area is front instep.Warms up in about 1 minute and the feet get warm.M is about US 6-12; L is about US 8-14. High Quality Warm Socks:Rechargeable heated socks are made of cotton polyester spandex.Function of absorbent,breathable,quick-drying and elasticity.Soft Padded reinforced heel & toe.Prevent your feet from getting cold.Suggest:Hand wash under normal temperature. Applications:Daily Wear,foot care,especially suitable for outdoor sports and activities of various kind of harsh environments,Even in the mountain climbing, hiking, running, outdoor cycling, water sports, snow sports, adventure, hunting, fishing, outdoor gardening and so on. Package Included:(1) one pair heated socks ,(2) 2*3.7V 2200mah li-ion batteries,(3) 1*AC charger (4)1* using manual.Powered by 3.7V Rechargeable li-ion batteries with Over-Voltage Protection.NOTE: When the charging adapter's light turns green that means the batteries are full charged. Ideal Gift in Winter:Heated socks are given to your family and friends as winter ideal gifts.It is a perfect for those chilly arthritis foot and Chronically Cold Feet & Stiff Joints People.this rechargeable socks will give your feet warm all winter.If you have any problems,please contact us by email.