A method for delivering liquids is disclosed wherein a quantity of the liquid is provided within a cell within a cassette. The cassette is received within a sleeve having an open end. A flap at the open end of the sleeve extends inwardly through the open end between the sleeve and cassette to abut a lip on the cassette and hold the cassette therein. Impingement of the flap pushes the flap away from the lip to allow the cassette to move out of the sleeve. A label mounted within the sleeve rotates between a viewable position where it is visible through a window in the sleeve and a retracted position away from the window. Extraction and reinsertion of the cassette into the sleeve moves the label from the viewable to the non-viewable position.