Chartpak AD Markers are designed for artists, designers and architects. These xylene-based markers have a single nib that will produce three distinct line widths with a mere shift of the wrist. The unique nib shape gives the user precise control over each stroke, and colors blend easily when wet yet hold when dry. AD Marker Colorless Blender makes it possible to acheive unlimited color gradations and pastel tones. Blend color already applied to your art surface or use it as you would a paint brush. For mixing, apply AD Marker colors to a nonabsorbent surface (mylar, glass, foil, etc...), pick up color with the Blender and apply it to your art surface. A clean Blender can be used to pick up unwanted color while still wet. Tip: Keep your Blender's Tri-Nib clean and spotless by wiping with a paper towel after use.