Helps protect RV plumbing and hoses from damage caused by high-pressure city water. High flow regulator allows 15 Percent to 20 Percent more water flow. Easy to read dial shows PSI and kPa. Attaches easily with convenient 3/4 Inch garden hose threads. Pressure is factory pre-set at 40 To 50 PSI (green zone). Yellow zone indicates less than 40 PSI and the red zone indicates pressures above 50 PSI. Patent pending