Tombow Eraser MONO Zero Round 23mm Black The innovative eraser MONO zero is available with two differently formed tips for precise erasing: Round tip in 2.3 mm diameter and rectangular tip in 2.5 x 5 mm. It is an essential utensil for all professional or recreational use that requires pinpoint erasing. The slim casing is available in different colours, including a striking neon assortment (round tip only). The MONO zero has a push mechanism with metal lead. It is easily refillable.