Rule has rotatably linked outer elements, one with movable insert provided with same length measurement units as outer element

摘要

The rule consists of strip-shaped element (1) arranged in series with adjacent elements rotated joined at the ends so that they form a rule when unfolded to 180 degrees and to which length measurement units are applied. At least one outer element has a movable insert (2) provided with the same length measurement units as the outer element.