The proprietary liquid ink technology in Karin Brushmarker PRO Markers maintains the ink's color intensity down to the last drop. These colors can be mixed and lightened to achieve tonal transitions in your artwork. For drawing, illustration, and design. Flexible, durable nylon tips. - Karin Brushmarkers Pro Markers and Sets - Set of 12, Gray ColorsKarin Brushmarker Pro, 12 GRAYS - Includes Cool Gray 1, Cool Gray 2, Cool Gray 3, Warm Gray 1, Warm Gray 2, Warm Gray 3, Neutral Gray 1, Neutral Gray 2, Neutral Gray 3, Olive Green, Olive Gray, and Black.