Closure units for containers

A closure unit for an opening in a container comprising a cup assembly having first and second opposite ends and adapted to be received in the opening, a downtube having an end portion within the assembly and projecting from said first end of the assembly, the down-tube providing an inner passage while an outer passage is provided between said end portion and the assembly, and inner and outer concentric valve members associated with the inner and outer passages respectively and spring biased to close said passages, wherein the cup assembly comprises (1) a component of plastics material having a collar adjacent to said second end of the assembly and a plurality of legs projecting from the collar to said first end of the assembly and (2) a reaction ring received within the legs adjacent to said first end and surrounding the downtube, the ring forming a reaction member for the spring means acting on the outer valve member and having abutment means which are forced by the spring means into engagement with oppositely facing abutment means on the legs, the component being such that the legs are sufficiently resilient to be sprung apart to allow the ring to be inserted into position between the legs from said first end during assembly of the closure unit, and an outer ring embracing the legs adjacent to said first end to prevent the legs springing apart in the assembled closure.