Abstract: The invention relates to a connector device for establishing fluid communication between a first and a second container. The device includes a first tube member for engaging the first container and a second tube member in fluid communication with said first tube member at a first end and having at a second end an engagement member for engagement of said second container. The second tube member includes a second piercing means. The engagement member allows, in an activated position, for piercing of the second container by the second piercing means and prevents separation of the second container and the device, so that the piercing of the second container cannot be undone, and so that the second container cannot be separated from the connector device after it has been pierced.