One is a pre-dispersed black pigment blended with a unique method giving a distinct advantage over all other black pigments. One goes in smooth & easy & wont dry up or harden in the ink cap. One also cleans up easily off the skin. Recommended for all uses; lining, shading, cover-ups & cut your tribal time in half!! One makes incredible washes when diluted with distilled water. The name says it all, One, specially designed for one pass.