Uni-ball Signo UM-151 Gel Ink Pen - 0.38 mm - 5 Color Set 5 Color Set (Black,Red,Pink,Light Blue,Orange) Smooth wring and hard to ooze. High viscosity gel ink becomes liquid by revolving of the tip ball. Ink written once on paper attemps to resume to gel. Pigment ink is superior in water resistance, light resistance.