While not in the same class as high grade furbearers like beaver, otter or mink, the gray wolf's fur is nonetheless thick and durable, and is primarily used for scarfs and the trimmings of women's garments, though it is occasionally used for jackets, short capes, coats, mukluks and rugs. Aside from bodily protection and adornment, gray wolf pelts have also been used as camouflage in hunting and warfare, as an insignia among western Native Americans and as a form of currency. The quality of wolf peltries rests on the density and strength of the fur fibre, which keeps the fur upright and gives the pelt an appealing bushy aspect. These characteristics are mostly found in northern wolf populations, but gradually lessen further south in warmer climates. North American wolf pelts are among the most valuable, as they are silkier and fluffier than Eurasian peltries. In Medieval Europe, pelts were considered the only practical aspect of wolves, though they were seldom used, because of the skin's foul odour. In Scandinavian folklore, wolf-skin girdles assisted in transforming the wearers into werewolves, while several Native American tribes used wolf pelts for medicinal purposes. Plains Indians often wore wolf pelts as disguises to get close to American bison when hunting. The Pawnee wore wolf skins as capes when exploring enemy territories. The United States Army used wolf skin for parkas during the later stages of World War II and the Korean War to protect the faces of soldiers from frostbite. In the Soviet Union, 30,000 wolf pelts were produced annually between 1976 and 1988. Statistics from CITES indicate that 6,000–7,000 wolf skins are internationally traded each year, with Canada, the former Soviet Union, Mongolia and China being the largest exporters, and the United States and Great Britain being the largest importers. Overall, the harvesting of wolves for their fur has little impact on their population, as only the northern varieties (whose numbers are stable) are of commercial value. Wolf trapping for fur remains a lucrative source of income for many Native Americans.