Ensure precise removal of sketching and drawing mistakes with this fantastic derwent eraser pen the eraser is fitted in a convenient pen shape with comfort grip so you can accurately rub away any mistakes without the risk of ruining the rest of your work or the paper you can shape the eraser to form the perfect shape with a craft knife use the retractor to extend or remove the eraser strip to replace with a new one small convenient and accurate freedom to sketch without the worry of oops