Rule of weights and measures of metal profiles (Machine-translation by Google Translate, not legally binding)

摘要

Rule of weights and measures of metal profiles, essentially characterized by a set of three discs, a central one of greater diameter and two exteriors both revolving on the central one by means of an axis that holds the set and that, the central disc has printed the measures that interest to know and in its extreme part that of classes of profiles, and the two external discs carry a translucent arrow by which the indications that the central disc takes as they move are appreciated. (Machine-translation by Google Translate, not legally binding)