Pressure is controlled by preset regulating units (RU) that screw into the regulator body.
Inside each RU is a spring that absorbs the force of the water without restricting the flow.
Each RU is capable of regulating between 6-20 gpm. The larger sizes have more RUs to handle a typical flow rate in that diameter hose.
12 PSI 35 PSI
15 PSI 50 PSI
20 PSI 65 PSI