This pack of 2 Honeywell 22mm motorised 2 port zone valves have a wide range of flow control applications in domestic and light commercial central heating systems. V4043H (normally closed) models have end switches for electrical control of pump and/or boiler.Spring return actionManual lever for filling/draining the systemPowerhead replaceable without draining downPotential free end switch for electrical control of pump and/or boilerQuiet operationMinimal power consumption