Genuine suburban brand anode rod for all suburban hot water systems.
Surburban RV Hot Water Systems use an anode rod which absorbs all the corrosive action of hot water. Located on the bottom of the HWS under the main burner, you simply unscrew this to drain the tank of water.
If the rod is mostly eaten away, simply replace it with a new one. It is important to do this regularly. It is good practice to check the rod every time you drain your hot water service.