Staedtler mars lumograph pencils are premium-quality blacklead pencils for writing, drawing and sketching on paper and matt drawing film. The wide range of degrees makes Lumograph the ideal tool for artists and graphic designers. The lines reproduce well and the pencils are both easy to erase and easy to sharpen with any quality sharpener. The pencils are unbelievably break-resistant due to special lead formulation and super-bonded lead. The lead diameter is 2 mm.