Lightfast Colour Pencils, Professional Quality, Wooden Box Set of 100, 2305693. 100% Lightfast, all colours are professional quality and comply with ASTM 6901 and Blue Wool Scale ISO 105 Revolutionary Oil-Based core which creates rich vibrant colour Colours can be mixed on the page to create a paint-like effect Strong point for detailed drawing and layering techniques A rich colour selection, with quick and opaque colour laydown.