Spectra AD Markers by Chartpak are a range of 95 alcohol-based dual tip markers and a colorless blender. Spectra AD have brilliant color and less odor than the traditional xylene-based AD Markers. Designed with the artist in mind, Spectra AD Markers have vibrant colors, maximum ink draw-out, and are ergonomically designed. These markers feature a tri-nib on one end and a brush nib on the other end. The tri-nib can be used to create thin, medium and thick widths, while the flexible brush nib creates smooth lines that change with pressure. Use the Colorless Blender marker to blend and lighten colors or create subtle gradations of color. Available individually and in sets. Fast-drying, permanent and non-toxic.