The present invention relates in part to multi-chambered vessels comprising a first chamber a second chamber and a seal comprising a first member and a second member, wherein the first member and the second member are engageable with one another to form a barrier separating the first chamber and the second chamber. The first member and the second member are disengageable from one another to open a channel between the first chamber and the second chamber. Vessels of the invention allow a user to establish communication between the first chamber and the second chamber at a desired time, for example in order to contact components contained within the chambers or in order to sequentially release components or doses of components from the vessel. Also provided is a kit comprising a seal of the invention. The kit advantageously allows a single-chambered vessel (for example a bottle or a syringe) to be converted into a multi-chambered vessel capable of controlling communication between the chambers at the final stage of the filling process.
