The #1 selling lead in the world and the industry standard. 1.3mm lead is strong, heavy-duty and high-quality. Write smoother, bolder, darker lines on a variety of surfaces. Proprietary lead Formula and thickness resists breaking. Extra-thick lead creates a dark imprint that is ideal for writing, drawing, sketching, marking, etc. And does not leave heavy impressions on your paper. 1.3mm lead is available in b and HB lead hardness.