Abstract: One or more dimensions of each of a series of similar manufactured elements, which are formed of magnetizable materials such as iron, steel, nickel or the like may be quickly checked for conformity to a predetermined value by momentarily positioning each successive element against an electromagnetic sensing device. The sensing device has a winding establishing a magnetic flux path through a core which is formed with one or more gaps in the magnetic circuit that are located to be spanned by a wrongly dimensioned or wrongly oriented one of the manufactured elements. Spanning of a flux gap of the core by a wrongly dimensioned or misoriented element changes the self-inductance value of the winding, and circuit means are provided for detecting such change in order to indicate the presence of a disconforming element or to actuate mechanism for rejecting or correcting the element.