Om Mechanical pencil
High Quality Content by WIKIPEDIA articles! A mechanical pencil (U.S. English) or a propelling pencil (UK English) is a pencil with a replaceable and mechanically extendable solid pigment core called a lead ( /EE lEd/). It is designed such that the lead can be extended as its point is worn away. The lead is not bonded to the outer casing and is usually graphite based, though colored pigments and other solid substances are also used.