Ceramic roller ball pens are a classic for any pen lover. The pen writes with a smooth yet sharp feeling that you can’t get with some other gel pens. This nicely designed ceramic roller ball pen refill by Ohto is available in four sizes: 0.4 mm, 0.5 mm, 0.7 mm and 1.0 mm. It comes in a standard body size so may fit other ceramic ball pens.