Derwent USB eraser, this brilliant little machine isn´t for erasing stray lines – it´s actually an incredible tool for creating light/white lines and patterns in drawings made with pencil, pastels, crayons and to some extent, watercolours. With practice and a gentle touch, you can even slowly bring out lighter shades of the colour you are erasing, without removing it completely. Charge with the accompanying USB lead to give the 500mAh lithium-ion battery a long-lasting charge. 10 large erasers, 5 mm, and 10 small erasers, 2.4 mm in diameter are also included. Please note that the start button seen in the picture is only on one side.