This is a female threaded tap connector with a 3/4" BSP thread.  It incorporates a fine gauze particle filter which is easily removed for cleaning.

Screws directly onto any tap with a Male 3/4" BSP thread (common on most outdoor garden taps)

This item also has a male Snap On connection which enables the connection of a standard 1/2" (ID) garden hose.  A female snap On hose connector is required to attach the hose.  

It can also be used to fill watering cans and other containers with filtered water without attaching a hose pipe.