Use this Copic Ink neutral gray refill to replenish the ink in your Copic makers and extend the life of their use and to reduce plastic waste. The nozzle is designed to reach the barrel on the inside of the pen and the cap is designed to match the fill color so it's easy to match the ink refill to the coordinating marker. The following are refill rates per marker type: Sketch—About 1.8ml (about 7 times), Ciao—About 1.4 ml per time (about 9 times), Classic—About 2.5 ml per time (about 5 times) , Wide—About 3.4 ml per time (about 3.5 times). Details: Available in multiple neutral gray colors 0.59" x 0.59" x 5.51" (1.5cm x 1.5cm x 14 cm) individual refill size0.4 fl. oz. (12 mL) internal liquid capacity Permanent and non-toxic Dries acid-free Alcohol dye ink For use with Sketch, Ciao, Classic and Wide Copic markers CAUTION: Copic Ink is alcohol-based and flammable. Keep away from direct sunlight and extreme temperatures. Keep out of reach of children. Use in a well-ventilated area.