The formula is secret the pencil is world-famous! - It was with pencils that STAEDTLER s success story began. - To this very day, first-class materials and manufacturing processes guarantee outstanding and unbeatable product quality. - STAEDTLER Mars Lumograph is available in up to 16 degrees for writing, drawing and sketching on paper and matt drafting film. - The super-bonded lead wears evenly and is easy to erase and sharpen.