This pressure switch includes quick connect fittings and automatically turns the booster pump on when pressure in the system is low, and turns the pump off when pressure is high (for example when the pressure tank is full or when a float valve closes).  Has two plastic electrical plugs compatible with other Aquatec products.  Turn the set screw clockwise to increase the OFF pressure setting and counter clockwise to decrease. The screw should not be adjusted more than one turn. Excessive adjustment of the pressure switch could cause low system pressure, and rapid ON/OFF cycling, reducing pump and motor life. Damage may occur if recommended maximum pressures are exceeded. The Warranty does not cover improper adjustment of the pressure switch.  When the pressure is adjusted, the difference between the high and low pressure settings remain apx. 20 psi.