Choose the "Close-To-The-Ultimate" boot sock for extreme warmth and as-good-as-it-gets moisture regain properties (the ability of a fiber to hold water without feeling wet or clammy). Bison down has a moisture regain 12 times greater than comparable wool.
They are exceptionally durable, and perfect for non-exertive outdoor activities such as still hunting, winter wade fishing, cold-weather equipment operation, snowmobiling.
Machine washable. 28% Bison/28% yak/27% nylon/14% silicon polyester/3% Lycra spandex. Full terry-loop knitting. Nylon over-plating for abrasion resistance. Knit exclusively for Herd Wear/Buffalo Gold by Cabot Hosiery, Northfield, VT.
(Oh ... we do not know what the "Ultimate" boot sock might be .... but we are working on it. Until then, this is as warm, as durable and as comfortable as it gets ... promise!)