The invention relates to an assembly (100) comprising : - a connecting member (20) to be mounted on a first medical container, - an adaptor (10) comprising: o a gripping member (30) to be mounted on a second medical container, o 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.
