Copic Markers 6-Piece Sketch Set, Perfect Primaries Packaged in a clear plastic case, a sketch set is the ideal way to begin or add to a marker collection Refillable markers and replaceable nibs, compatible with copic air brush system Alcohol-based ink is pemranent and non-toxic, dries acid free Markers are dual-tipped and have a different nib on each end. One end is the Sketch nib and the other is the Ciao nib.