Screw cap intended to remain attached to a container after opening the container , characterised in that it comprises: - a cylindrical wall having a first longitudinal axis , a first end closed by a bottom and a second end open, the cylindrical wall having an internal surface comprising a thread arranged to cooperate with a thread arranged on a neck of the container , the cylindrical wall being configured to be alternatively in a closed position in which the cylindrical wall is screwed onto the neck and an open position in which the cylindrical wall is unscrewed from the neck and the neck is open, the cylindrical wall comprising a portion forming a tab extending between an attachment tip and a free tip parallel to the first longitudinal axis , the tab having longitudinal edges parallel to the first longitudinal axis ; - a security ring extending the cylindrical wall and intended to be retained on the neck by a retaining element arranged on the container , the security ring being connected to the second end of the cylindrical wall by at least one fracturable connection , the fracturable connection being arranged to fracture upon a first unscrewing of the cylindrical wall ; - two arms each having a first end and a second end , the arms moving away from each other symmetrically on either side of the tab towards the second end connected to the security ring , characterised in that the attachment tip is connected to the cylindrical wall by a hinge ; in that the tab furthermore has at least one slot with a second longitudinal axis substantially parallel to the first longitudinal axis , the slot or slots having a width (L) orthogonal to the second longitudinal axis ; and in that the first end of each of the arms is joined to a longitudinal edge of the tab , the arms being arranged to pull on either side of the tab allowing an enlargement of the width (L) of the slot or slots upon displacement of the cylindrical wall along the first longitudinal axis during unscrewing of the cylindrical wall . - a cylindrical wall having a first longitudinal axis , a first end closed by a bottom and a second end open, the cylindrical wall having an internal surface comprising a thread arranged to cooperate with a thread arranged on a neck of the container , the cylindrical wall being configured to be alternatively in a closed position in which the cylindrical wall is screwed onto the neck and an open position in which the cylindrical wall is unscrewed from the neck and the neck is open, the cylindrical wall comprising a portion forming a tab extending between an attachment tip and a free tip parallel to the first longitudinal axis , the tab having longitudinal edges parallel to the first longitudinal axis ; - a security ring extending the cylindrical wall and intended to be retained on the neck by a retaining element arranged on the container , the security ring being connected to the second end of the cylindrical wall by at least one fracturable connection , the fracturable connection being arranged to fracture upon a first unscrewing of the cylindrical wall ; - two arms each having a first end and a second end , the arms moving away from each other symmetrically on either side of the tab towards the second end connected to the security ring , characterised in that the attachment tip is connected to the cylindrical wall by a hinge ; in that the tab furthermore has at least one slot with a second longitudinal axis substantially parallel to the first longitudinal axis , the slot or slots having a width (L) orthogonal to the second longitudinal axis ; and in that the first end of each of the arms is joined to a longitudinal edge of the tab , the arms being arranged to pull on either side of the tab allowing an enlargement of the width (L) of the slot or slots upon displacement of the cylindrical wall along the first longitudinal axis during unscrewing of the cylindrical wall . <EOS>