The Mitsubishi Hi-Uni 6B pencil (http://www.jetpens.com/product_info.php/cPath/620_621/products_id/2945) glides smoothly on card stock leaving rich dark marks. Given the softness of its lead core, it tends to blunt quickly. Excellent choice for quick doodling and the final shading stage of a drawing. Would make a nice addition and increase the expressive range of any graphite drawing kit.

Comparison chart of five 6B graphite pencils showing the expressive range from lightest gray to deepest black attainable with each brand. While all sample swatches might look fairly similar, the Faber-Castell pencils required more strokes to reach that same degree of darkness. All the pencils felt quite smooth on the card stock, but the Staedtler Mars Lumograph pencil felt a bit drier and crumbled the most from this bunch. The Tombow Mono and the Mitsunishi Hi-Uni seemed to glide faster and very smoothly on the paper producing their darkest shades with fewer strokes.