Writes on all plastics, glass, metal, wood, paper and cloth, including PTFE fluoropolymer resins. A precision seal valve provides smooth ink flow and preserves the pen's life, even if it's left uncapped. When dry, the solvent based ink is temperature resistant from 0°C to 155°C (32°F to 310°F). Markings are insoluble in water or hydrocarbons, resists many solvents, and are easily removed with alcohol. Box of 12 pens, assorted colors or 12 of a single color.