Monolith Selection Tin Unique set for writing and sketching. Exclusive design, 6 grades (HB-9B) + water soluble 4B and accessories. Monolith Graphite Pencils are pure graphite in a pencil with a thin lacquer coating. Six levels of hardness: 9B 8B 6B 4B 2B HB Different types of graphite are mixed with ceramic clay and then finely ground to produce a high quality lead. The proportion of graphite to clay determines the softness and darkness of the lead.