Jacobson & Johnson
Rolling ruler having a retractable and rotatable pivot pin
 A multipurpose ruler to permit a user to precisely draw geometric shapes as well as to store information including a housing having a rotatable roller with multiple information areas and an alignment mark to permit the user precisely align the ruler for accurately drawing geometric figures. A retractable pivot pin permits the user to draw circles about the pivot pin and a transparent housing permits a user to readily view information stored on the ruler. 
B B
B43L B43L
inventional inventional
Wei
Wang