Rheem PROTECH anode rods are an important line of defense in preventing corrosion and leaks in your water heater. These devices work because the metal in the rod is sacrificed so the tank does not corrode. As the anode works, the life of the water heater is increased. The anode should be checked and replaced every couple of years. Direct replacement for Rheem, Ruud and Richmond water heaters Fits most brands check diameter of your current rod to ensure proper fit Helps prolong the life of your water heater (sold separately) Magnesium construction 3/4 in.