Pencil sharpener pencil in position, although they then sharpen them to the usual conical point as for a round pencil, abandoning some distinctive aspects of the carpenter's pencil. Sharpeners with a single blade for use on wax crayons are available, and sometimes included in boxes of crayons. These often have plastic blades, which are adequate for the soft wax. Mechanical pencils dispense the graphite lead progressively during use and thus do not require sharpening; such pencils are sometimes called "self-sharpening". A type of mechanical pencil has a rotating gear mechanism which rotates the lead slightly every time the lead is lifted off
Lead (tack) if they will not respond to a regular lead. A lead can be made from a variety of materials, including cotton, horsehair (woven or braided hair, usually from a horse's tail), leather, nylon or other synthetic materials. Lead ropes, as the name implies, are round and made of various types of rope, usually between 5/8 and 3/4 inch (about 2 cm) in diameter. Lead lines are usually flat webbing or leather, and are generally wide, though may be narrower for show use. Flat lines are less bulky and more comfortable in the hand for leading and animal, but may lack