The Water Stop from GARDENA is a practical hose fitting  for quickly and easily changing watering accessories.  The adapter is attached to the end of the hose and the auto water stop function cuts off the water flow immediately and only starts again as soon as you connect a new watering accessory, such as a spray nozzle, to the hose without you having to turn the tap off.  For use on 19mm (3/4″) hose pipes.