The handles of knives can be made from a number of different materials, each of which has advantages and disadvantages. Handles are produced in a wide variety of shapes and styles. Handles are often textured to enhance grip. Wood handles provide good grip and are warm in the hand, but are more difficult to care for. They do not resist water well, and will crack or warp with prolonged exposure to water. Modern stabilized and laminated woods have largely overcome these problems. Many beautiful and exotic hardwoods are employed in the manufacture of custom and some production knives. In some countries it is now forbidden for commercial butchers' knives to have wood handles, for sanitary reasons.[citation needed] Plastic handles are more easily cared for than wooden handles, but can be slippery and become brittle over time.[3] Injection molded handles made from higher grade plastics are composed of Polyphthalamide, and when marketed under trademarked names such as Zytel or Grivory, are reinforced with Kevlar or fiberglass. These are often used by major knife manufacturers. Rubber handles such as Kraton or Resiprene-C are generally preferred over plastic due to their durable and cushioning nature. Micarta is a popular handle material on user knives due to its toughness and stability. Micarta is nearly impervious to water, is grippy when wet, and is an excellent insulator. Micarta has come to refer to any fibrous material cast in r sin. There are many varieties of micarta available. One very popular version is a fiberglass impregnated resin called G-10. Leather handles are seen on some hunting and military knives, notably the KA-BAR. Leather handles are typically produced by stacking leather washers, or less commonly, as a sleeve surrounding another handle material. Skeleton handles refers to the practice of using the tang itself as the handle, usually with sections of material removed to reduce weight. Skeleton handled knives are often wrapped with parachute cord or other wrapping materials to enhance grip. Stainless steel and Aluminum handles are durable and sanitary, but can be slippery. To counter this, premium knife makers make handles with ridges, bumps, or indentations to provide extra grip. Another problem with knives that have metal handles is that, since metal is an excellent heat-conductor, these knives can be very uncomfortable, and even painful or dangerous, when handled without gloves or other protective handwear in (very) cold climates. A traditional knife handle made of buffalo horn from Tasikmalaya, Indonesia More exotic materials usually only seen on art or ceremonial knives include: Stone, bone, mammoth tooth, mammoth ivory, oosik (walrus penis bone), walrus tusk, antler (often called stag in a knife context), sheep horn, buffalo horn, teeth, mop (mother of pearl or "pearl") etc. Many materials have been employed in knife handles.