There is a locking device so that you can keep the same proportion on your drawing Scale divider can be used to your desired subject matter in the small end of the divider and transfer the spacing of the larger end to your drawing surface Proportional dividers are accurate, pocket-sized, and require no special electronics, so they are popular tools in these fields Easy to use Increase, decrease or measure the size of a subject to draw The scale divider tool is not only an essential tool for architects, but also an essential tool for art workers, Manufacturer: THOANBY