Derwent Onyx is made from smooth dark graphite and delivers dense, rich, jet-black tones, darker than a Graphic 9B. Due to its non-crumbly texture, the 4mm wide core is capable of sharpening and holding a fine point. This makes it equally good for quick expressive sketches, as well as detailed technical and architectural drawings. Darker shades can be built up by applying increased pressure. For lighter, more detailed artwork apply less pressure. Available in two tones, Medium and Dark.