Abstract: A shutoff device designed for the capping of semi-rigid packages composed of non-vitreous, non-metallic flexible sheet material, such as those cartons containing sterilized food products, for example, fruit juices and milk. The reusable shutoff device includes a base connected integrally with the package by the supporting surface, and the tooth cutting member, the sleeve connected with the base by the threaded joint, and the cap connected with the sleeve by the splined joint. Between the supporting surface and the cylindrical part of the base the flexible bridge is made, and the sleeve has the pusher, which is acting on the weakened element arranged at the bottom of the cap. The shutoff device improves the visual demonstrativeness of the indication of the initial unsealing of the package and makes the package easy to use.