Product Description Smooth fine tip black gel ink. Push the tail to retract. BCmini gel pen uses a gel-based ink, combining the permanence of oil-based ballpoint ink and the smooth glide of water-based ink, in which pigment is suspended in a water-based gel. Gel ink is thick and opaque, it shows up more clearly on dark or slick surfaces than the typical inks used in ballpoint or felt tip pens.