The invention relates to an assembly (100) comprising : - a connecting member (20) to be mounted on a first medical container, - an adaptor (10) comprising : ? a gripping member (30) to be mounted on a second medical container, ? a pierceable elastomeric piece (40), fixed with respect to said gripping member (30), - a protecting envelope (50) comprising a rigid shell (51) substantially surrounding said connecting member (20) and said adaptor (10) in a storage position of the assembly, in which the connecting member is separate from the adaptor, said rigid shell being closed by a removable film (52), wherein said assembly further comprises temporary fixing means (27 55) for preventing said connecting member (20) from escaping from said rigid shell (51 ) when said film (52) is removed. The invention further relates to a kit comprising such an assembly, a first and a second medical containers.
