WIDE USE - These double outliner drawing pens are great for arts crafts school projects coloring stamping Gift cards Greeting cards Christmas cards DIY Craft Projects Personality Posters Paintings Photo album. Also suitable for almost any surface 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 on the surface a few times to pump the ink until it starts to flow. For best results re-cap the markers immediately after use and store horizontally. Suggest to write on paper with 80gsm above Otherwise slight strike through will happen.