These double outliner drawing pens are great for arts, and crafts, school projects, coloring, stamping, Gift cards, Greeting cards, Christmas cards, DIY Craft Projects, Posters, Paintings, and Photo albums. Also suitable for almost any such as metal, pottery, wood, rubber, glass, plastic, stone, etc. *12 COLORS METALLIC DOUBLE LINE PENS *EASY TO USE - With the cap on, shake the marker well to mix the ink. Take off the cap and gently press down the tip a few times to pump the ink until it starts to flow. Re-cap the markers immediately after use for best results and store them horizontally. Suggest writing on paper with 80gsm above, Otherwise, a slight strike-through will happen.