Camco 11533 4.5&rdquo; Anode Rod with Drain for Atwood Aluminum Water Heater 4.5 Magnesium Rod for Atwood style aluminum hot water heaters It preserves the life of the water heater by corroding itself so the water heater tank doesn't Internal drain valve allows to drain your water heater without tools Includes internal drain valve that allows draining of the water heater without tools 1/2-14NPT thread