Control ring

Control ring for a fastener comprising an enlarged head and a cylindrical shaft extending along an axis, the shaft comprising at least one band of coating parallel to the axis, the band extending over a circumferential width, the ring comprising a cylindrical tubular body extending along an axis of revolution between a first extremity and a second extremity, characterized in that

• the first extremity comprises two adjacent arc segments, each arc segment having an end wall extending in a plane perpendicular to the axis of revolution of the ring, the planes of the two walls not being one and the same and being axially offset from the first extremity;
• and
• each arc segment comprises at least one side wall extending over a radial plane going through the axis of revolution of the ring;
• and in that
• a width of an arc segment is defined by a minimum band width to be checked, and a cumulative width of the two arc segments is defined by a maximum band width to be checked.