This specification applies to indicating ammeters and voltmeters, of both flush and projecting types, intended for panel mounting and having: for round flush types, a flange diameter not exceeding 3½ in, and body diameter not exceeding 2¾ in.; for projecting types, a body diameter not exceeding 2¾ in.; for square flush types, a length or breadth over the flanges not exceeding 2¼ in. The specification provides for both terminal stud and plug-in types.