Both the E550 and F550 feature an 8mm diameter orifice, this and the 90º flow path ensure that the 550 offers excellent flow characteristics for this class of valve. The F550 is especially designed cope with the build-up of lime scale. The E550 and F550 types are available with optional flow control and vent tube. The solenoid coil can be fitted with a DIN style IP65 connector.