Constrained Ball

It’ll be the smartest tool in your pencil boxes. To draw straight lines, locate the “Constrained Ball” at the tip of the pen, move the drawing aid and then done! So with this writing tool, everybody can draw straight lines without the help of a ruler. But that’s not all, as the tool is also equipped with a measuring wheel that allows the users to draw desired line length in three directions—horizontal, vertical and 45-degree angle.