The uni-ball Signo UM-120 contains superior quality, ultra smooth gel ink, making them perfect for various arts and crafts activities. The ink is quick drying, and will not smudge and smear, as well as fade proof and waterproof. They are especially unique as they can be written on black paper. This smooth rollerball pen has a 0.7 fine tip which allows the easy flow of gel continuously for extra smooth writing.