Device for connection with a closed container

Device for connection to a closed container, said container comprising a neck an opening of said neck being plugged by a stopper made of relatively soft material, and provided with an external annular lip, the connection device comprising:

• a cap designed to fit coaxially over the neck of the container plugged with the stopper, elastic radially outwards so that it can snap-fasten over the annular lip of the neck, the cap comprising a coaxial collar lengthening it and forming an internal bore,
• a transverse wall for coming into contact with an external part of the stopper, and
• means for connection with the inside of the container through the stopper, comprising a piston mounted so that it can slide in a bore of the collar of the cap, a central needle passing through the piston and having one end for perforating the stopper,
• wherein in combination, the cap is designed to fit directly over the neck of the container, the transverse wall is made of a relatively hard material for coming directly to bear against the external part of the stopper and includes a central opening for the passage of the central needle of the connection means, and the device furthermore includes, on the one hand, an external sleeve designed to slide coaxially against and on the outside of the internal cap, including a circumferentially continuous band provided along one of its edges with an internal annular ridge for snap-fastening under a free rim of the internal cap which is radially elastic enough to fit tightly against the internal cap and snap-fasten by means of the annular ridge under the free edge but is strong enough to be indivisible and means for protecting the connection means from the outside, in leaktight contact with the collar of the cap.