Most diverter valves screw onto most standard taps which have a male thread available after removing the aerator. If you haveĀ a female thread, this adapter will be required.
They come with a range of different thickness washers which you pack inside the longer threaded end so as to just sit proud of the end or in some cases a bit higher if your tap requires it to seal off properly. This end is screwed up into the tap spout and the diverter valve is then screwed onto the shorter thread end.