Copic Ink is an alcohol-based ink that does not dissolve and works well with watercolors and colored pencils. Copic Sketch, Original, and Ciao markers are refillable by using this fast-drying, permanent and non-toxic ink. To refill the markers, match the color number on the marker with the corresponding ink color number. Markers can be refilled by dabbing the ink directly onto the broad nib using the attached nozzle or use your Copic Nib Tweezers to remove the nib, making refills even quicker. This 12ml ink will be able to refill all markers approximately 5-8 times, depending on the type of marker. This refill works with the following Copic Markers: Copic Sketch Marker - Forest Green - G17 Copic Original Marker - Forest Green - G17 Copic Ciao Marker - Forest Green - G17