Embodiments of a device for protecting and sealing the opening of a container, especially for containers used in experimental and diagnostic laboratories. This device is a one-piece made plug (1) for a flask or container, comprising at least one passing channel (2), and at least one structural flow regulator barrier, allowing the passing of solid elements. The structural regulator barrier comprises at least a gate (4) to regulate the passing and connection between the inside space and the outside space of the container in a unidirectional and/or bidirectional way. The plug may be made of an elastomeric material (8) and is resealable. It is not necessary to remove the plug to acces a sample contained in the container. An embodiment includes a method and a mold for manufacturing such a device.
