What kind of socks may you send in a Military care package?

[Common Sense is Knocking]

I am sending a care package to my brother's unit in Afghanistan. He told me he would like to receive some socks and underwear. The guy that emails the families gave a list of acceptable brands, but I lost the list. I plan on getting it there by Christmas, so I'm sending them by Wednesday. What brands do they accept for socks and underwear? What do soldier's prefer?


Thanks!
Like what brands? I know they have to be pretty thick to resist flammable damage. Anyone have specific brands and what I should look for?