M88FX alcohol based, pigmented ink, valve activated markers are recommended for heavy duty use. The marks are permanent, weatherproof, UV resistant and fast drying and the pen will mark on wood, plastic, rubber and metal. Reversible tip with 3mm bullet and 5mm chisel ends. Contains 13ml of ink. Xylene free, HAPS free (Hazardous air pollutants), Prop 65 Compliant.