Tombow MONO Knock Erasers are ideal for erasing on the move, whether you’re sketching out or writing down your creative ideas. These pen-style erasers are refillable with an easy to use push button advance, just like a mechanical pencil. A convenient clip allows artists and writers to easily store this eraser, while the rubber grip and it’s 3.8mm round body make this a comfortable in hand. this eraser deserves a spot in the pencil cases of artists, writers and students alike! Allows for extremely precise erasing, and is excellent for charcoal.