These sets feature collections of Chameleon Color Tones Markers - the markers that give you the ability to change the color tone of your pen! Each pen produces multiple color tones, giving artists the ability to create stunning effects such as 3D, smooth transitions, highlighting, shading, gradations and blending, all with one pen. The markers are refillable and all nibs are replaceable. This set includes NG4 Neutral Gray 4, CG5 Cool Gray 5, CG9 Cool Gray 9, WG3 Warm Gray 3, WG7 Warm Gray 7. Recommended for ages 14 and up.