Uni-Ball Signo Broad Point Gel Impact Pen Blue Black Ink Refills, 1.0mm, Set of 5 (Japan import) [Komainu-Dou Original Package] Refill for Uni-Ball Signo UM-153.64 Broad Point Gel Ink Pen Ink color: Blue Black The diameter of a ball: 1.0 mm. Bold letter type.