These thin-profile socks blend 60% merino wool with 25% brushtail possum fiber — a natural insulator with a hollow hair structure that traps heat efficiently while staying lightweight. Possum fiber is 55% warmer than merino alone and 14% lighter, making it a high-performance choice for cold-weather outdoor activity without added bulk. The blend is naturally antimicrobial and quick-drying, reducing odor and moisture buildup over extended wear. Crafted in New Zealand by William Ellery.