The cleverly formed ONBOOK fits perfectly the spine or cover of a note book. It would not stick out, slip or fall off and stays, due to its bean-shaped face and thin and strong clip, exactly where you want it. The writing instrument is available as ballpoint pen and mechanical pencil, which differ by a fine button at the body of the ballpoint pen to retract the lead. The pencil has a handy eraser in its push-button.