An adapter, suitable for use with a can that has a valve cup around a stationary valve stem housing in which a depressible valve stem resides and that extends out from a or is accessible through only the top of the valve stem housing, the adapter comprising a base, a neck and a bendable segment connecting the base and the neck and having a flow channel extending all the way through the base, bendable segment and neck, the adapter further comprising a plunger attached to the neck or bendable segment and extending within the flow channel of the bendable segment towards and optionally into the flow channel of the base, where: (a) the base has opposing bottom and top ends with a base side wall extending between the bottom and top with the flow channel extending through an entrance opening defined through the bottom and extending between the top and bottom; (b) the bendable segment has opposing bottom and top ends with a bendable segment side wall extending between the bottom and top with the bottom attached to the top of the base so that the flow channel extends between the top and bottom of the bendable segment within the bendable segment side wall, where the bendable segment side wall comprises a compressible feature; (c) the neck has opposing bottom and top ends with a neck side wall extending between the bottom and top with the bottom attached to the top of the bendable segment so that the flow channel extends between the top and bottom of the neck, within the neck side wall and through an exit opening defined through the top of the neck; and (d) the plunger is of dimensions and/or design so as to allow fluid communication around and/or through it within the flow channel; wherein: when the bendable segment is tilted with respect to the base, the plunger extends further down along the flow channel of the adapter towards the entrance opening of the base, and configured that, in use, with said can the plunger extends far enough down in the flow channel so as to depress the depressible can valve stem for opening the can valve, and; when the bendable segment is returned from a tilted position to its neutral position, the plunger retracts upward in the flow channel away from the entrance opening of the base, and wherein the flow channel extends in a straight line from the entrance opening of the base through the exit opening of the neck when the bendable segment is in its neutral position, and characterized in that the adapter base, when attached to the valve, is free of any portion that fastens to the valve cup by extending over a top of the valve cup and the base has threads defined on an outer surface of the base side wall; defined on an inner surface of the base side wall within the flow channel proximate to the entrance opening of the base; or defined on the outer surface of the base side wall and on the inner surface of the base side wall within the flow channel proximate to the entrance opening of the base. (a) the base has opposing bottom and top ends with a base side wall extending between the bottom and top with the flow channel extending through an entrance opening defined through the bottom and extending between the top and bottom; (b) the bendable segment has opposing bottom and top ends with a bendable segment side wall extending between the bottom and top with the bottom attached to the top of the base so that the flow channel extends between the top and bottom of the bendable segment within the bendable segment side wall, where the bendable segment side wall comprises a compressible feature; (c) the neck has opposing bottom and top ends with a neck side wall extending between the bottom and top with the bottom attached to the top of the bendable segment so that the flow channel extends between the top and bottom of the neck, within the neck side wall and through an exit opening defined through the top of the neck; and (d) the plunger is of dimensions and/or design so as to allow fluid communication around and/or through it within the flow channel; when the bendable segment is tilted with respect to the base, the plunger extends further down along the flow channel of the adapter towards the entrance opening of the base, and configured that, in use, with said can the plunger extends far enough down in the flow channel so as to depress the depressible can valve stem for opening the can valve, and; when the bendable segment is returned from a tilted position to its neutral position, the plunger retracts upward in the flow channel away from the entrance opening of the base, and wherein the flow channel extends in a straight line from the entrance opening of the base through the exit opening of the neck when the bendable segment is in its neutral position, and characterized in that the adapter base, when attached to the valve, is free of any portion that fastens to the valve cup by extending over a top of the valve cup and the base has threads defined on an outer surface of the base side wall; defined on an inner surface of the base side wall within the flow channel proximate to the entrance opening of the base; or defined on the outer surface of the base side wall and on the inner surface of the base side wall within the flow channel proximate to the entrance opening of the base.