What is the difference between 0.9 0.7 and 0.5 lead?

The difference between 0.9, 0.7, and 0.5 lead primarily lies in their hardness and composition. The numbers indicate the percentage of graphite in the pencil lead, with 0.9 being the hardest and most dense, followed by 0.7, and then 0.5, which is the softest. Harder leads produce finer, lighter lines, while softer leads create darker, bolder strokes. This variation allows users to choose the appropriate lead based on their drawing or writing needs.