Castell 9000 pencils have superior leads made of finely ground graphite and clay. These smooth, pure graphite pencils are never scratchy and are great for drawing and sketching. The full length of the lead is glued to the wood casing of the pencil to strengthen the lead and prevent breakage, which allows for better sharpening and produces a fine point. The specialized sets contain pencils in degrees of accurately graded, exclusively formulated leads. The 12-Pencil Design Set includes grades 5B through 5H those particularly suited to meet the needs of a designer.