The Feed Valve is an essential part used in home water purification devices (such as refrigerators and others) to connect the water source to the filter. Feed Valve (1/4 inch) compatible with Naqi filters: It is installed on the water adapter (Bush 3/8) to supply the purification device with water. Size: The valve outlet is designed to fit external pipes with a diameter of 6 mm (quarter inch). A durable metal feed valve is available to ensure no leakage.