Abstract: An assembly is provided comprising a container and a break-off closure made of plastic. The container comprises a surface with a passage opening, which opening is sealed by the break-off closure An attachment area is provided between the break-off closure and the surface of the container, which area is situated around and at a distance from the circumference of the passage opening. The attachment being obtained by heating the attachment surface of one of the container and break-off closure to such a temperature that a breakable attachment is formed between them.