Derwent Onyx pencils are made from smooth dark graphite and allow you to instantly create dense rich jet-black tones, even darker than a Graphic 9B.
Their 4mm wide core has a non-crumbly texture which means they will sharpen and hold a fine point for longer making them ideal for hatching. They will also smudge, allowing you to blend with your fingertip or a Tortillon.
They are equally good for quick expressive sketches as well as for detailed technical and architectural drawings. If you require really deep tones these can be built up by applying increased pressure. Less pressure will achieve lighter tones ideal for more precise work.