The present invention relates in part to vessels comprising a first chamber a second chamber and a seal separating the first and second chambers. In particular, the invention concerns means and methods for establishing communication between the first chamber and a second chamber of such vessels. Vessels of the invention may comprise one or more projections on an internal wall of the vessel and an actuator configured to cause the seal and the one or more projections to engage one another. The one or more projections are configured to urge a portion of the seal away from the internal wall upon engagement with the seal. This causes one or more channels to open 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.
