Tested to -13 degrees Fahrenheit (-25 degrees Celsius), the Bridgedale Men's Endurance Summit Sock is the warmest and most cushioned sock by Bridgedale. Perfect for year around mountain expeditions and extended outdoor pursuits, this heavyweight sock features high density yarn throughout the foot to provide extra protection and impact resistance. Bridgedale's unique Woolfusion technology yarn blends a high content of moisture absorbing New Wool with wicking Endurofil. This pulls excess moisture away from the foot ensuring lasting comfort and blister control. Targeted knitting around the ankle defines a deep heel pocket and easy ankle flex zone to maintain a precise fit. The sculpted heavyweight cushioning provides extra comfort and protection in the Achilles-heel and toe box area. The men's Bridgedale Endurance Summit Sock is designed for use with full-height high volume footwear in cold conditions.