The Spectra AD Markers are extremely versatile markers making them ideal for art and design. They are brilliant alcohol based markers featuring dual ended tips with a flexible brush tip on one side, and a unique tri-nib on the other. The AD Marker signature tri-nib offers three line widths - fine, medium, and broad - with the twist of the wrist. Colors dry fast, are permanent, and non-toxic. They can be used with the Spectra AD Blender Marker to blend, lighten and graduate colors. Spectra AD Markers can be used with traditional xylene-based AD Markers. Conforms to ASTM D-4236.