The present invention also provides a liquid reservoir assembly 10 of the type that can store and release a fluid under pressure, the assembly 10 having an outer body formed of an open ended tube 20 which is closed by end formations 70, 80 which engage respective ends of the open ended tube 20 and are held stationary with respect to the open ended tube 20, the end formations 70,80 holding between them an elongated elastic inner tube 30 sealing secured to the end formations, the elastic inner tube 30 being axially pre-tensioned or stretched from its natural or rest state, and secured to the ends in the pre-tensioned or stretched condition.