Abstract: A valve is fitted to a reservoir containing a pressurized product. The valve has a valve body made of an elastomeric material and an activation element for, in response to an actuation command, causing the valve to move from a closed position into a position which allows the product to be dispensed. The valve body includes a first mounting device to allow the valve to be mounted in a first position in which the valve body defines, with an edge of an opening in the reservoir, at least one passage communicating with the reservoir, so as to allow the reservoir to be filled with a propellent gas. A second mounting device allows the valve to be mounted in a second position in which the valve body is mounted in a sealed fashion on the edge of the opening in the reservoir. A container fitted with this valve and a method of packing it are also disclosed.