Use this Copic Ink Refill to refill Sketch & Ciao markers by dabbing the ink directly onto the nib or by removing the nib with tweezers for quicker filling. Refills offer the ability to custom mix colours. Measurements are marked on the bottle. The tip is angled for accurate filling. One bottle of permanent ink will refill a Ciao marker thirteen times and Sketch marker eight times. These inks are marked with universal colour numbers for each Copic Marker. Cleans up with rubbing alcohol.