Screw capping device intended to remain tethered to a container after opening of the container, comprising a cylindrical wall having a longitudinal axis, an end closed by a bottom and an open end, the cylindrical wall comprising a first section comprising the closed end and a second section comprising the open end, the second section extending the first section according to the longitudinal axis, the first section having an inner surface comprising a threading arranged to co-operate with a threading arranged on a neck of the container, the first section being configured to be alternatively in a closed position wherein the first section is screwed on the neck and an open position, wherein the first section is unscrewed from the neck and the neck is open, the second section having an inner surface comprising a projecting circular element arranged to co-operate with a retaining element arranged on the container to retain the second section to the container, the first section being connected to the second section by a circumferential junction comprised in a plane perpendicular to the longitudinal axis, the circumferential junction comprising a non-breakable connection extending symmetrically over a first predetermined distance on either side of a generator of the cylindrical wall and a first breakable connection completing the circumferential junction, the second section further comprising a second breakable connection extending parallel to the circumferential junction, the second breakable connection extending symmetrically over a second predetermined distance on either side of the generator of the cylindrical wall, the second predetermined distance being greater than the first predetermined distance, the first breakable connection and the second breakable connection being able of being broken during a first unscrewing of the first section, characterized in that the second breakable connection has a rounded portion facing the non-breakable connection, the rounded portion having a peak opposite the circumferential junction. comprising a cylindrical wall having a longitudinal axis, an end closed by a bottom and an open end, the cylindrical wall comprising a first section comprising the closed end and a second section comprising the open end, the second section extending the first section according to the longitudinal axis, the first section having an inner surface comprising a threading arranged to co-operate with a threading arranged on a neck of the container, the first section being configured to be alternatively in a closed position wherein the first section is screwed on the neck and an open position, wherein the first section is unscrewed from the neck and the neck is open, the second section having an inner surface comprising a projecting circular element arranged to co-operate with a retaining element arranged on the container to retain the second section to the container, the first section being connected to the second section by a circumferential junction comprised in a plane perpendicular to the longitudinal axis, the circumferential junction comprising a non-breakable connection extending symmetrically over a first predetermined distance on either side of a generator of the cylindrical wall and a first breakable connection completing the circumferential junction, the second section further comprising a second breakable connection extending parallel to the circumferential junction, the second breakable connection extending symmetrically over a second predetermined distance on either side of the generator of the cylindrical wall, the second predetermined distance being greater than the first predetermined distance, the first breakable connection and the second breakable connection being able of being broken during a first unscrewing of the first section, characterized in that the second breakable connection has a rounded portion facing the non-breakable connection, the rounded portion having a peak opposite the circumferential junction.