The product landed and it all became clear! The Dry sock is not actually a sock! The name relates more to the effect rather than the product. Using this will give you dry socks in the morning...
What am I babbling about? Basically, the Dry Sock is a large sausage shaped bean bag, filled with what I suspect is silica gel. You shove it in your damp, sweaty shoes and let it do it's business. Pull it out in the morning and you are good to go.
Hang the product up in the aerated bag (provided) in a well ventilated place and the Dry Sock recharges itself ready for next time.