Darn Tough OTC Heavyweight Sock – Full Cushion | Merino Wool Over-the-Calf Socks

Extreme Cold Weather OTC Tactical Boot Socks – Full Cushion

Maximum Warmth. Rugged Terrain Ready. Mission Approved.

When the temp drops and the terrain gets unforgiving, this is the sock you reach for. The Extreme Cold Weather/Mountaineering Over-the-Calf (OTC) Sock is the warmest and tallest sock in the tactical lineup. Built for freezing environments and high-exertion missions, these heavyweight Merino wool socks deliver full-cushion comfort, reinforced durability, and zero quit.

Whether you’re on duty, training in the elements, or deployed into the mountains, these over-the-calf tactical boot socks are engineered to work as hard as you do. Berry Compliant, USAF Safe to Fly Certified, and NAVAIR SOA Approved, they meet strict military standards—while still being soft, breathable, and built to outlast the mission.

Why We Love It:

These are not your standard-issue socks. They’re Made in the USA from Merino wool that wicks moisture, regulates temperature, and holds heat even when wet. That means no slipping, no blisters, and no regrets—just full tactical readiness from heel to cuff.

Ideal For:

• Military Combat Boots

• Tactical Boots

• OCP Uniforms

• Mountaineering

• Extreme Cold Weather Deployments

Specs:

• Height: OTC
  
• Weight: Heavyweight
  
• Cushion: Full Cushion
• Pair with: Military combat boots, tactical boots, ocp boots
  
• Style Number: T4050

Details:

• Tactical over the calf socks average 17 in. from heel to cuff – expect them to cover the leg to just below the knee.
• A performance fit means no slipping, no bunching, no blisters – so you can focus on your mission and not your feet.
• Berry Amendment compliant tactical socks are knit with Merino Wool that’s raised, sourced, and produced in the USA.
• US Air Force Safe to Fly certified, meeting Flame Resistant and No Melt No Drip requirements for wearing next to skin under approved flame resistant combat and utility uniforms.
• A military-grade fiber, Merino Wool protects foot health and is ultra-durable in the toughest conditions.
• Heavyweight socks hold heat and are breathable and padded for full protection in cold weather.
• The “still” in Still Made in Vermont, USA is personal. We knit all our socks at our VT-based Mills – we can’t imagine it any other way.
• Unconditionally Guaranteed for Life – if these aren’t the longest lasting socks you’ve ever owned, return them for another pair.
• USAF Safe to Fly Certified and NAVAIR SOA Approved

Materials + Care:

• Machine wash in cold water on gentle cycle with socks inside-out. Do not bleach. Tumble dry on low or hang dry. Do not dry clean. You can learn more about how to wash merino wool socks here.
• Materials: 79% Merino Wool 20% Nylon 1% Lycra Spandex (*Fiber percentages of socks may vary slightly.)

Size + Fit: