Roger Hayter was thinking very hard :
The one supplied with our shower had two sizes of taper, and they
suggested matching it to the shower head. At the other end it is held
only by the threaded outlet and washer, the outer taper is not engaged.
The existence of two sizes is a slight concern.

The threaded sleeves on the shower flexibles, where they attach to the
outlet and the head, are captive on the hose. You cannot swap them
without wrecking the hose.