The Merino Blend Heated Crew Length Socks feature a soft merino wool blend construction with heat under the toes for subtle, targeted warmth. The high-capacity battery provides between 4-16 hours of heat between charges (depending on the heat setting), and you have the added convenience of adjusting temperature right from the wireless remote control. For those who don&';t like above-the-calf socks and want long heat times, this is the sock for you.