The Hozelock Pressure Regulator reduces your tap water pressure for automatic watering systems, and includes connectors for both 13mm and 4mm hose. An accessory adaptor also allows you to fit the pressure regulator onto a hose connector. It is recommended a regulator should be used in automatic watering installations as it optimises the water pressure of the system. It will fit both 1/2in and 1/4in BSP taps, and will connect direct to a tap, water controller, or even to the end of a hose. Compatibility 13mm, 4mm.