A closure (10) for mounting at an opening (O) of a container spout (S) comprises a compartment (32) in which material such as a tablet (T) can be positioned. The compartment comprises a wall (26) that comprises a first region (28) that is surrounded by a second bellows-like region (30) that enables the first region to be displaced from a first position to a second position to cause the material to be released from the compartment. The wall can comprise a protrusion (X) that extends into the compartment such that, when the wall is displaced to the second position, the protrusion can cause the material to be released from the compartment. Also, when the wall is displaced to the second position the first region can act directly on the material to force it out of the compartment.