3/4" Zero PSI valve perfect for low pressure gravity fed system or a rain catchment system where there is very low pressure and a traditional electric irrigation valve will not open and close properly. This inline valve is 110 v operated and requires the Outdoor Heavy Duty Timer ( see SKU #122688) to open and close the valve. Traditional electric valves used in drip irrigation systems require pressure to open and close the valves properly. Gravity or rain catchment systems usually do not have enough pressure to open and close the valve properly. This valve is the perfect way to use the water from these kinds of low pressure or Zero pressure systems.