Commonly called mechanical pencils, these make sketching or writing in the field clean and easy. Leads can be inserted into either end, just slip the
Porte Crayon
Pencil - Stationery Wiki
DMP - Dave's Mechanical Pencils: 2007
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DMP - Dave's Mechanical Pencils: 2007
Pencil - Stationery Wiki
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DMP - Dave's Mechanical Pencils: 2007
DMP - Dave's Mechanical Pencils: 2007
National Museum of American History
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DMP - Dave's Mechanical Pencils: 2007
DMP - Dave's Mechanical Pencils: 2007