UK Northwest Frontier Socks Heavyweight double woven khaki wool socks that were worn by the Indian Army on duty in the high country around the Khyber Pass. These were especially popular for wear with Chaplis sandals. In North Africa they were the mark of veteran campaigners.
Used by by all services for carrying rations, horse fodder, the colonel's laundry, etc. Don't let the RSM catch you at kit inspection without your stringbag.