Koh-I-Noor Hardtmuth Carpenter Flat Sketching Pencil - 6B is a thick rectangular lead encased in a special flat oval wooden envelope. Ideal for use by carpenters and joiners. Suitable for broad and thin strokes as well as calligraphy. Extra-wide graphite core allows you to work with broad strokes; good for quick, loose sketching, shading, or filling in large areas.