Abstract: Container closure (10) engageable with a container having an interior for containing a fluid, water or drink, the container closure adapted to allow mixing of the fluid and a second material. The closure (10) has a movable mouthpiece (12), a fluid opening which is associated with sealing means (28, 29) adapted to substantially seal the fluid opening in a first position and allow fluid to flow in a second position. The closure also has a regulation ring (27) with bulbous portion (30) that can open and close an opening to a reservoir (13) containing the second material. The first fluid and second material are mixed in a passage prior to exiting the container closure.