pencil barrel

A mechanical pencil, also clutch pencil, is a pencil with a replaceable and mechanically extendable solid pigment core called a "lead" . The lead, often made of graphite, is not bonded to the outer casing, and can be mechanically extended as its point is worn away as it is being used. Other names include microtip pencil, automatic pencil, drafting pencil, technical pencil, click pencil, pump pen, pump pencil, leadholder, pacer (Australian English), propelling pencil (Australian English), pen pencil (Indian English), and lead pencil (Bangladeshi and American English).
Mechanical pencils are used to provide lines of constant width without sharpening in technical drawing and in quick, neat writing. They have also been used for fine-art drawing. Since they do not have to be sharpened, they are also very popular with students. Mechanical pencils were first used in the 18th century, with many designs patented in the 19th and 20th centuries.

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