What Our Gearhead(R) Experts Are Saying: "This is my pick for winter boots and cold-weather shoes. The merino top keeps feet warm and fresh, and the mid-arch support feels balanced without being aggressive. The extra heel cushioning makes a big difference on long days in the cold." We reach for the Thermo X Mid Arch Insole when temperatures drop and comfort becomes even more important. BootDoc pairs its trusted 3-Arch Concept support with a merino wool top layer, creating an insole that adds warmth without sacrificing stability or fit. The merino top cover naturally regulates temperature and helps keep feet feeling fresh, while the rearfoot stabilizer guides alignment through each step. Added heel cushioning softens impact on hard winter surfaces, making this insole a reliable choice for cold-weather footwear, daily wear, and long hours on your feet. Thoughtful support and cozy comfort, built for winter conditions.