The k4 full control can help you find the right pressure setting ensuring an optimal clean simply choose the correct spray lance based on the surface you wish to clean using the surface symbols on the spray lances as a guide once you have chosen the lance you wish to use just twist the vario lance to find the correct pressure setting guided by the led display on the trigger gunthis k4 model is perfect for tackling medium sized patios and cars yet powerful enough to tackle tough dirt with